r336806: buildworld failed: emmintrin.h file not found

[Samy Mahmoudi]

---- Basic/SourceManager.o ----
/usr/src/contrib/llvm/tools/clang/lib/Basic/SourceManager.cpp:1175:10 fatal
error: 'emmintrin.h' file not found
#include <emmintrin.h>
              ^------------------
The file is located at
/usr/src/contrib/llvm/tools/clang/lib/Headers/emmintrin.h but I do not know
how to properly indicate this to the build suite.