Compressor misses XY+CZ swap

[notmgsk]

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Eric says

It isn't hurting anyone to include this, but I'd expect the peephole rewriter to figure this out on this on its own. Rather, what I mean is: it would be worrying to me if the compressor didn't pick up on this on its own. Is that the case?

I added a specific translator in #649 to allow this particular swap optimization, but it ought to be achieved without any special machinery.