Support for custom build toolchains (apache#330)

* Support for custom build toolchains

ISSUE apache#297

Locate the header file path of DORIS_GCC_HOME, add them to the CPLUS_INCLUDE_PATH environment variable.
So clang can find it.

* Compatible with custom toolchain for clang

ISSUE apache#297

1. Find default header file paths of DORIS_GCC_HOME and set as enviroment variable CLANG_COMPATIBLE_FLAGS.
2. Explicitly add these paths to CLANG_INCLUDE_FLAGS.

be/CMakeLists.txt

@@ -408,7 +408,12 @@ message(STATUS "${LINUX_VERSION_LOWER}")
 #     message(FATAL_ERROR "Currently not support system ${LINUX_VERSION}")
 # endif()
 
+if(DEFINED ENV{CLANG_COMPATIBLE_FLAGS})
+    set(CLANG_COMPATIBLE_FLAGS $ENV{CLANG_COMPATIBLE_FLAGS})
+endif()
+
 message(STATUS "CLANG_BASE_FLAGS: ${CLANG_BASE_FLAGS}")
+message(STATUS "CLANG_COMPATIBLE_FLAGS: ${CLANG_COMPATIBLE_FLAGS}")
 
 set(CLANG_INCLUDE_FLAGS
     "-I${LLVM_HOME}/include"
@@ -419,6 +424,7 @@ set(CLANG_INCLUDE_FLAGS
     "-I${THIRDPARTY_DIR}/include/event/"
     "-I${GPERFTOOLS_HOME}/include"
     ${CLANG_BASE_FLAGS}
+    ${CLANG_COMPATIBLE_FLAGS}
 )
 
 # Set include dirs

env.sh

@@ -80,3 +80,8 @@ if [[ ! "$(printf '%s\n' "$required_ver" "$gcc_ver" | sort -V | head -n1)" = "$r
     exit 1
 fi
 
+# export CLANG COMPATIBLE FLAGS
+export CLANG_COMPATIBLE_FLAGS=`echo | ${DORIS_GCC_HOME}/bin/gcc -Wp,-v -xc++ - -fsyntax-only 2>&1 \
+                | grep -E '^\s+/' | awk '{print "-I" $1}' | tr '\n' ' '`
+
+