Add an ammintrin.h header for SSE4a intrinsics.

This is a clean-room implementation based on public documentation and
I tried to validate it as much as possible against gcc.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@157638 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed