LegalizeDAG.cpp uses the value of the comparison operands when checking
the legality of BR_CC, so DAGCombiner should do the same.
v2:
- Expand more BR_CC value types for NVPTX
v3:
- Expand correct BR_CC value types for Hexagon, Mips, and XCore.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176694 91177308-0d34-0410-b5e6-96231b3b80d8