The MachineOperatorReducer was only reducing word32 expressions of the type x << y | x >>> (32 - y) (and variants) to the equivalent Word32Ror. This CL applies the same pattern-matching logic to Word32Xor.

BUG=

Review-Url: https://codereview.chromium.org/2199323003
Cr-Commit-Position: refs/heads/master@{#38284}