[IR] Match intrinsic parameter by scalar/vectorwidth

This patch replaces the existing LLVMVectorSameWidth matcher with LLVMScalarOrSameVectorWidth.

The matching args must be either scalars or vectors with the same number of elements, but in either case the scalar/element type can differ, specified by LLVMScalarOrSameVectorWidth.

I've updated the _overflow intrinsics to demonstrate this - allowing it to return a i1 or <N x i1> overflow result, matching the scalar/vectorwidth of the other (add/sub/mul) result type.

The masked load/store/gather/scatter intrinsics have also been updated to use this, although as we specify the reference type to be llvm_anyvector_ty we guarantee the mask will be <N x i1> so no change in behaviour

Differential Revision: https://reviews.llvm.org/D57090

llvm-svn: 351957