[X86][AVX512][Clang][Intrinsics] Adding missing intrinsics to Clang .

Summary:
Adding missing intrinsics :
    _mm512_set_epi16,
    _mm512_set_epi8,
    _mm512_permutevar_epi32
    _mm512_mask_permutevar_epi32

Reviewers: zvi, guyblank, eladcohen, craig.topper

Reviewed By: craig.topper

Subscribers: craig.topper, cfe-commits

Differential Revision: https://reviews.llvm.org/D31034

llvm-svn: 298208