[Driver] Fix missing MultiArch include dir on powerpcspe

On powerpc-linux-gnuspe, the header files are located in their
own include directory named /usr/lib/powerpc-linux-gnuspe,
so add this directory to PPCMultiarchIncludeDirs.

Patch by glaubitz (John Paul Adrian Glaubitz)

Differential Revision: https://reviews.llvm.org/D52066

llvm-svn: 342231

clang/lib/Driver/ToolChains/Linux.cpp

@@ -699,7 +699,8 @@ void Linux::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
       "/usr/include/mips64el-linux-gnu",
       "/usr/include/mips64el-linux-gnuabi64"};
   const StringRef PPCMultiarchIncludeDirs[] = {
-      "/usr/include/powerpc-linux-gnu"};
+      "/usr/include/powerpc-linux-gnu",
+      "/usr/include/powerpc-linux-gnuspe"};
   const StringRef PPC64MultiarchIncludeDirs[] = {
       "/usr/include/powerpc64-linux-gnu"};
   const StringRef PPC64LEMultiarchIncludeDirs[] = {