Ensure target gcc headers can be included

There are a few headers installed as part of the OpenEmbedded
gcc-runtime target (omp.h, ssp/*.h). Being installed from a recipe
built for the target architecture, these are within the target
sysroot and not cross/nativesdk; thus they weren't able to be
found by gcc with the existing search paths. Add support for
picking up these headers under the sysroot supplied on the gcc
command line in order to resolve this.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>

Upstream-Status: Pending

--- a/gcc/Makefile.in	2014-12-23 11:57:33.327873331 +0000
+++ b/gcc/Makefile.in	2015-01-21 11:32:35.447305394 +0000
@@ -587,6 +587,7 @@
 
 # Directory in which the compiler finds libraries etc.
 libsubdir = $(libdir)/gcc/$(target_noncanonical)/$(version)
+libsubdir_target = gcc/$(target_noncanonical)/$(version)
 # Directory in which the compiler finds executables
 libexecsubdir = $(libexecdir)/gcc/$(target_noncanonical)/$(version)
 # Directory in which all plugin resources are installed
@@ -2534,6 +2535,7 @@
 
 PREPROCESSOR_DEFINES = \
   -DGCC_INCLUDE_DIR=\"$(libsubdir)/include\" \
+  -DGCC_INCLUDE_SUBDIR_TARGET=\"$(libsubdir_target)/include\" \
   -DFIXED_INCLUDE_DIR=\"$(libsubdir)/include-fixed\" \
   -DGPLUSPLUS_INCLUDE_DIR=\"$(gcc_gxx_include_dir)\" \
   -DGPLUSPLUS_INCLUDE_DIR_ADD_SYSROOT=$(gcc_gxx_include_dir_add_sysroot) \
--- a/gcc/cppdefault.c	2015-01-13 17:40:26.131012725 +0000
+++ b/gcc/cppdefault.c	2015-01-21 11:30:08.928426492 +0000
@@ -59,6 +59,10 @@
     /* This is the dir for gcc's private headers.  */
     { GCC_INCLUDE_DIR, "GCC", 0, 0, 0, 0 },
 #endif
+#ifdef GCC_INCLUDE_SUBDIR_TARGET
+    /* This is the dir for gcc's private headers under the specified sysroot.  */
+    { STANDARD_STARTFILE_PREFIX_2 GCC_INCLUDE_SUBDIR_TARGET, "GCC", 0, 0, 1, 0 },
+#endif
 #ifdef LOCAL_INCLUDE_DIR
     /* /usr/local/include comes before the fixincluded header files.  */
     { LOCAL_INCLUDE_DIR, 0, 0, 1, 1, 2 },
diff --git a/gcc/defaults.h b/gcc/defaults.h
index f94ae17..d98b40b 100644
--- a/gcc/defaults.h
+++ b/gcc/defaults.h
@@ -1390,4 +1390,13 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 
 #endif /* GCC_INSN_FLAGS_H  */
 
+/* Default prefixes to attach to command names.  */
+
+#ifndef STANDARD_STARTFILE_PREFIX_1
+#define STANDARD_STARTFILE_PREFIX_1 "/lib/"
+#endif
+#ifndef STANDARD_STARTFILE_PREFIX_2
+#define STANDARD_STARTFILE_PREFIX_2 "/usr/lib/"
+#endif
+
 #endif  /* ! GCC_DEFAULTS_H */
diff --git a/gcc/gcc.c b/gcc/gcc.c
index 9f0b781..174fca8 100644
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -1189,13 +1189,6 @@ static const char *gcc_libexec_prefix;
 
 /* Default prefixes to attach to command names.  */
 
-#ifndef STANDARD_STARTFILE_PREFIX_1
-#define STANDARD_STARTFILE_PREFIX_1 "/lib/"
-#endif
-#ifndef STANDARD_STARTFILE_PREFIX_2
-#define STANDARD_STARTFILE_PREFIX_2 "/usr/lib/"
-#endif
-
 #ifdef CROSS_DIRECTORY_STRUCTURE  /* Don't use these prefixes for a cross compiler.  */
 #undef MD_EXEC_PREFIX
 #undef MD_STARTFILE_PREFIX