[AVX-512] Remove masked pmin/pmax intrinsics and autoupgrade to native IR.

Clang patch to replace 512-bit vector and 64-bit element versions with native IR will follow.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@284955 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed