clover: Add --with-clang-libdir option and verify CLANG_RESOURCE_DIR

$CLANG_RESOURCE_DIR is the directory that contains all resources
needed by clang to compile programs.  When clover uses clang to
compile kernels it needs to specify a resource dir, so that clang
can find its internal headers (e.g. stddef.h).

clang defines $CLANG_RESOURCE_DIR as $CLANG_LIBDIR/clang/$CLANG_VERSION

This patch adds the --with-clang-libdir option in order to accommodate
clang intalls to non-standard locations, and it also adds a check
to the configure script to verify that $CLANG_RESOURCE_DIR/include
contains the necessary header files.

configure.ac

@@ -1610,6 +1610,12 @@ AC_ARG_WITH([libclc-path],
    [LIBCLC_PATH="$withval"],
    [LIBCLC_PATH=""])
 
+AC_ARG_WITH([clang-libdir],
+   [AS_HELP_STRING([--with-clang-libdir],
+         [Path to Clang libraries @<:@default=llvm-config --libdir@:>@])],
+   [CLANG_LIBDIR="$withval"],
+   [CLANG_LIBDIR=""])
+
 AC_SUBST([LIBCLC_PATH])
 
 if test "x$enable_opencl" = xyes; then
@@ -1696,6 +1702,7 @@ AC_SUBST([LLVM_LIBS])
 AC_SUBST([LLVM_LDFLAGS])
 AC_SUBST([LLVM_INCLUDEDIR])
 AC_SUBST([LLVM_VERSION])
+AC_SUBST([CLANG_RESOURCE_DIR])
 
 case "x$enable_opengl$enable_gles1$enable_gles2" in
 x*yes*)
@@ -1870,6 +1877,16 @@ if test "x$enable_gallium_llvm" = xyes; then
 	LLVM_LIBDIR=`$LLVM_CONFIG --libdir`
 	DEFINES="${DEFINES} -DHAVE_LLVM=`echo $LLVM_VERSION | sed -e 's/\([[0-9]]\)\.\([[0-9]]\)/0x0\10\2/g'`"
 	MESA_LLVM=1
+
+	dnl Check for Clang interanl headers
+        if test "x$enable_opencl" = xyes; then
+            if test "x$CLANG_LIBDIR" = x; then
+                CLANG_LIBDIR=${LLVM_LIBDIR}
+            fi
+            CLANG_RESOURCE_DIR=$CLANG_LIBDIR/clang/${LLVM_VERSION}
+            AC_CHECK_FILE("$CLANG_RESOURCE_DIR/include/stddef.h",,
+                AC_MSG_ERROR([Could not find clang internal header stddef.h in $CLANG_RESOURCE_DIR Use --with-clang-libdir to specify the correct path to the clang libraries.]))
+        fi
     else
 	MESA_LLVM=0
     fi

src/gallium/state_trackers/clover/Makefile.am

@@ -24,7 +24,7 @@ libclllvm_la_CXXFLAGS = \
 	$(LLVM_CPPFLAGS) \
 	$(DEFINES) \
 	-DLIBCLC_PATH=\"$(LIBCLC_PATH)/\" \
-	-DCLANG_RESOURCE_DIR=\"$(LLVM_LIBDIR)/clang/$(LLVM_VERSION)/\"
+	-DCLANG_RESOURCE_DIR=\"$(CLANG_RESOURCE_DIR)\"
 
 libclllvm_la_SOURCES = \
 	llvm/invocation.cpp