[X86][XOP] Enable commutation for XOP instructions

Patch to allow XOP instructions (integer comparison and integer multiply-add) to be commuted. The comparison instructions sometimes require the compare mode to be flipped but the remaining instructions can use default commutation modes.

This patch also sets the SSE domains of all the XOP instructions.

Differential Revision: http://reviews.llvm.org/D7646

llvm-svn: 229267