Add immintrin meta header.

- This is the official way to get AVX intrinsics, we might want to disallow
  direct inclusion of avxintrin.h, just like GCC does.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111660 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed