[X86] Custom legalize (v2i32 (setcc (v2f32))) so that we don't end up with a (v4i1 (setcc (v4f32)))

Undef VLX, getSetCCResultType returns v2i1/v4i1 for v2f32/v4f32 so default type legalization will end up changing the setcc result type back to vXi1 if it had been extended. The resulting extend gets messed up further by type legalization and is difficult to recombine back to (v4i32 (setcc (v4f32))) after legalization.

I went ahead and enabled this for SSE2 and later since its always the result we want and this helps type legalization get there in less steps.

llvm-svn: 324822