InstCombine: Clean up foldLogOpOfMaskedICmps

No functional change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222229 91177308-0d34-0410-b5e6-96231b3b80d8
InstCombine: Fold away tautological masked compares

It is impossible for (x & INT_MAX) == 0 && x == INT_MAX to ever be true.

While this sort of reasoning should normally live in InstSimplify,
the machinery that derives this result is not trivial to split out.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222230 91177308-0d34-0410-b5e6-96231b3b80d8