[X86] Remove the ANDN check from EmitTest.

Remove the TESTmr isel patterns and add another postprocessing combine for TESTrr+ANDrm->TESTmr. We already have a postprocessing combine for TESTrr+ANDrr->TESTrr. With this we can give ANDN a chance to match first. And clean it up during post processing if we ended up with just a regular AND.

This is another step towards my plan to gut EmitTest and do more flag handling during isel matching or by using optimizeCompare.

llvm-svn: 350038