[DAGCombiner] fold or (xor x, y),? patterns

or (xor x, y), x --> or x, y
or (xor x, y), y --> or x, y
or (xor x, y), (and x, y) --> or x, y
or (xor x, y), (or x, y) --> or x, y

Reviewed By: foad

Differential Revision: https://reviews.llvm.org/D138401