[X86] Add new patterns for masked scalar load/store to match clang's codegen from r331958.

Clang's codegen now uses 128-bit masked load/store intrinsics in IR. The backend will widen to 512-bits on AVX512F targets.

So this patch adds patterns to detect codegen's widening and patterns for AVX512VL that don't get widened.

We may be able to drop some of the old patterns, but I leave that for a future patch.

llvm-svn: 332049