PATCH: DAGCombiner - Use correct value type when checking legality of BR_CC - Changes to NVPTX, Mips, Hexagon, MBlaze, X86, and XCore targets

[Tom Stellard]

Hi,

The attached patch fixes a bug where the DAGCombiner was passing the
MVT::Other value type to TLI.isOperationLegalOrCustom() for a BR_CC node.
LegalizeDAG uses the value type of the comparison operands, and I think
this is what the DAGCombiner should be using as well.

I've updated the *ISelLowering files for the affected targets, but
backend code owners should double check my work.

Thanks,
Tom