[X86] Auto upgrade VPCOM/VPCOMU intrinsics to generic integer comparisons

This causes a couple of changes in the upgrade tests as signed/unsigned eq/ne are equivalent and we constant fold true/false codes, these changes are the same as what we already do for avx512 cmp/ucmp.

Noticed while cleaning up vector integer comparison costs for PR40376.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351697 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed