[x86] use VPMOVMSK to replace memcmp libcalls for 32-byte equality

Follow-up to:
https://reviews.llvm.org/rL298775


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298933 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed