[DAGCombine] SimplifyNodeWithTwoResults - ensure same legalization for LO/HI operands (PR21207)

Consistently use (!LegalOperations || isOperationLegalOrCustom) for all node pairs.

Differential Revision: https://reviews.llvm.org/D53478

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347255 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed