Various fixes necessary to build the simulator under MSYS.

Make.defs

@@ -2,7 +2,7 @@
 # apps/Make.defs
 # Common make definitions provided to all applications
 #
-#   Copyright (C) 2011, 2014, 2016 Gregory Nutt. All rights reserved.
+#   Copyright (C) 2011, 2014, 2016, 2018 Gregory Nutt. All rights reserved.
 #   Author: Gregory Nutt <gnutt@nuttx.org>
 #
 # Redistribution and use in source and binary forms, with or without
@@ -58,10 +58,15 @@ endif
 
 # Tools
 
+ifeq ($(DIRLINK),)
 ifeq ($(CONFIG_WINDOWS_NATIVE),y)
   MKKCONFIG = $(APPDIR)\tools\mkkconfig.bat
   DIRLINK   = $(TOPDIR)\tools\link.bat
   DIRUNLINK = $(TOPDIR)\tools\unlink.bat
+else ifeq ($(CONFIG_WINDOWS_MSYS),y)
+  MKKCONFIG = $(APPDIR)/tools/mkkconfig.sh
+  DIRLINK = $(TOPDIR)$(DELIM)tools$(DELIM)copydir.sh
+  DIRUNLINK = $(TOPDIR)$(DELIM)tools$(DELIM)unlink.sh
 else
   MKKCONFIG = $(APPDIR)/tools/mkkconfig.sh
   DIRUNLINK = $(TOPDIR)/tools/unlink.sh
@@ -71,6 +76,7 @@ else
   DIRLINK   = $(TOPDIR)/tools/link.sh
 endif
 endif
+endif
 
 ifeq ($(WINTOOL),y)
   INCDIROPT = -w

platform/Makefile

@@ -1,7 +1,7 @@
 ############################################################################
 # apps/platform/Makefile
 #
-#   Copyright (C) 2013-2014, 2016-2017 Gregory Nutt. All rights reserved.
+#   Copyright (C) 2013-2014, 2016-2018 Gregory Nutt. All rights reserved.
 #   Author: Gregory Nutt <gnutt@nuttx.org>
 #
 # Redistribution and use in source and binary forms, with or without
@@ -41,23 +41,6 @@ DELIM ?= $(strip /)
 
 include $(APPDIR)$(DELIM)Make.defs
 
-# Platform-specific Appliction Support
-# Tool stuff
-
-ifeq ($(DIRLINK),)
-ifeq ($(CONFIG_WINDOWS_NATIVE),y)
-DIRLINK = $(TOPDIR)$(DELIM)tools$(DELIM)link.bat
-DIRUNLINK = $(TOPDIR)$(DELIM)tools$(DELIM)unlink.bat
-else
-DIRLINK = $(TOPDIR)$(DELIM)tools$(DELIM)link.sh
-DIRUNLINK = $(TOPDIR)$(DELIM)tools$(DELIM)unlink.sh
-endif
-endif
-
-ifeq ($(WINTOOL),y)
-INCDIROPT = -w
-endif
-
 # Directories
 
 GNUDIR      = gnu