DAGCombiner: Simplify inverted bit tests

Fold (xor (and x, y), y) -> (and (not x), y)

This removes an opportunity for a constant to appear twice.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181395 91177308-0d34-0410-b5e6-96231b3b80d8