[X86][Clang] Converting __mm{|256|512}_movm_epi{8|16|32|64} LLVMIR call into generic...

[X86][Clang] Converting __mm{|256|512}_movm_epi{8|16|32|64} LLVMIR call into generic intrinsics.

This patch is a part two of two reviews, one for the clang and the other for LLVM.
In this patch, I covered the clang side, by introducing the intrinsic to the front end.
This is done by creating a generic replacement.

Differential Revision: https://reviews.llvm.org/D31394a

llvm-svn: 299431