[X86] Stop promoting vector and/or/xor/andn to vXi64.

These promotions add additional bitcasts to the SelectionDAG that can pessimize computeKnownBits/computeNumSignBits. It also seems to interfere with broadcast formation.

This patch removes the promotion and adds isel patterns instead.

The increased table size is more than I would like, but hopefully we can find some canonicalizations or other tricks to start pruning out patterns going forward.

Differential Revision: https://reviews.llvm.org/D53268

llvm-svn: 345408