[AVX-512] Remove masked pmovzx/pmovsx builtins and autoupgrade them to selects and native zext/sext.

This mostly reuses earlier autoupgrade support for the sse and avx equivalents. Just needed to add the code to add the select.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286092 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed