[InstCombine] In foldXorToXor, move the commutable matcher from the LHS match...

[InstCombine] In foldXorToXor, move the commutable matcher from the LHS match to the RHS match. No meaningful change intended.

There are two conditions ORed here with similar checks and each contain two matches that must be true for the if to succeed. With the commutable match on the first half of the OR then both ifs basically have the same first part and only the second part distinguishs. With this change we move the commutable match to second half and make the first half unique.

This caused some tests to change because we now produce a commuted result, but this shouldn't matter in practice.

llvm-svn: 306800