[mips] MSA intrinsics header file

This patch adds the msa.h header file containing the shorter names for the
MSA instrinsics, e.g. msa_sll_b for builtin_msa_sll_b.

Reviewers: vkalintiris, zoran.jovanovic

Differential Review: https://reviews.llvm.org/D24674


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@281975 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Headers/CMakeLists.txt

@@ -48,6 +48,7 @@ set(files
   mmintrin.h
   mm_malloc.h
   module.modulemap
+  msa.h
   mwaitxintrin.h
   nmmintrin.h
   opencl-c.h