Communicate cc, cc_vendor to make via config.mk.

Details:
- Historically, the compiler selection has happened statically in the
  various make_defs.mk and would only be overriden by setting CC (either
  prior to running configure or as a configure argument). However, in
  the last couple months, configure has evolved to contain rather
  sophisticated compiler detection logic for the purposes of blacklisting
  sub-configurations. It only makes sense that configure now fully take
  over the responsibility of selecting a compiler from the GNU make side
  of the build system. Thanks to Alex Arslan for his help exposing this
  issue.
- Substitute found_cc into CC in config.mk via configure.
- Set a new variable, CC_VENDOR, in config.mk via substitution from
  configure, and disable the corresponding CC_VENDOR code in common.mk.
- Disabled default compiler selection (usually gcc) in the sub-configs'
  various make_def.mk files.

build/config.mk.in

@@ -82,6 +82,7 @@ endif
 
 # The C compiler.
 CC                := @CC@
+CC_VENDOR         := @CC_VENDOR@
 RANLIB            := @RANLIB@
 
 # The level of debugging info to generate.

common.mk

@@ -298,22 +298,22 @@ GIT_LOG    := $(GIT) log --decorate
 # --- Determine the compiler vendor --------------------------------------------
 #
 
-ifneq ($(CC),)
-
-VENDOR_STRING := $(shell $(CC) --version 2>/dev/null)
-ifeq ($(VENDOR_STRING),)
-VENDOR_STRING := $(shell $(CC) -qversion 2>/dev/null)
-endif
-ifeq ($(VENDOR_STRING),)
-$(error Unable to determine compiler vendor.)
-endif
-
-CC_VENDOR := $(firstword $(shell echo '$(VENDOR_STRING)' | $(EGREP) -o 'icc|gcc|clang|ibm|cc'))
-ifeq ($(CC_VENDOR),)
-$(error Unable to determine compiler vendor. Have you run './configure' yet?)
-endif
-
-endif
+#ifneq ($(CC),)
+#
+#VENDOR_STRING := $(shell $(CC) --version 2>/dev/null)
+#ifeq ($(VENDOR_STRING),)
+#VENDOR_STRING := $(shell $(CC) -qversion 2>/dev/null)
+#endif
+#ifeq ($(VENDOR_STRING),)
+#$(error Unable to determine compiler vendor.)
+#endif
+#
+#CC_VENDOR := $(firstword $(shell echo '$(VENDOR_STRING)' | $(EGREP) -o 'icc|gcc|clang|ibm|cc'))
+#ifeq ($(CC_VENDOR),)
+#$(error Unable to determine compiler vendor. Have you run './configure' yet?)
+#endif
+#
+#endif
 
 
 

config/amd64/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := amd64
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/arm32/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := arm32
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/arm64/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := arm64
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/bgq/make_defs.mk

@@ -42,10 +42,10 @@ THIS_CONFIG    := bgq
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := /bgsys/drivers/ppcfloor/comm/gcc.legacy/bin/mpixlc_r
-CC_VENDOR      := ibm
-endif
+#ifeq ($(CC),)
+#CC             := /bgsys/drivers/ppcfloor/comm/gcc.legacy/bin/mpixlc_r
+#CC_VENDOR      := ibm
+#endif
 
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You

config/bulldozer/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := bulldozer
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/cortexa15/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := cortexa15
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/cortexa57/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := cortexa57
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/cortexa9/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := cortexa9
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/excavator/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := excavator
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/generic/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := generic
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/haswell/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := haswell
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/intel64/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := intel64
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/knc/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := knc
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := icc
-CC_VENDOR      := icc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/knl/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := knl
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/penryn/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := penryn
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/piledriver/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := piledriver
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/power7/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := power7
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/sandybridge/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := sandybridge
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/skx/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := skx
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/steamroller/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := steamroller
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/template/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := template
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/x86_64/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := x86_64
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

config/zen/make_defs.mk

@@ -42,11 +42,6 @@ THIS_CONFIG    := zen
 # --- Determine the C compiler and related flags ---
 #
 
-ifeq ($(CC),)
-CC             := gcc
-CC_VENDOR      := gcc
-endif
-
 # NOTE: The build system will append these variables with various
 # general-purpose/configuration-agnostic flags in common.mk. You
 # may specify additional flags here as needed.

configure

@@ -2220,7 +2220,7 @@ main()
 	install_libdir_esc=$(echo "${install_libdir}" | sed 's/\//\\\//g')
 	install_incdir_esc=$(echo "${install_incdir}" | sed 's/\//\\\//g')
 	dist_path_esc=$(echo "${dist_path}"           | sed 's/\//\\\//g')
-	cc_esc=$(echo "${CC}" | sed 's/\//\\\//g')
+	cc_esc=$(echo "${found_cc}" | sed 's/\//\\\//g')
 	ranlib_esc=$(echo "${RANLIB:-ranlib}" | sed 's/\//\\\//g')
 
 	# Create a #define for the configuration family (config_name).
@@ -2292,6 +2292,7 @@ main()
 		| sed -e "s/@os_name@/${os_name}/g" \
 		| sed -e "s/@dist_path@/${dist_path_esc}/g" \
 		| sed -e "s/@CC@/${cc_esc}/g" \
+		| sed -e "s/@CC_VENDOR@/${cc_vendor}/g" \
 		| sed -e "s/@RANLIB@/${ranlib_esc}/g" \
 		| sed -e "s/@debug_type@/${debug_type}/g" \
 		| sed -e "s/@threading_model@/${threading_model}/g" \