Fuse "reverse"

Going through GHC/List.hs in base, I've noticed that reverse does not have any fusion rules at all. Although the version of the language report is a good consumer, it is currently unused, AFAIK because of previous versions of ghc having difficulities optimizing foldl. This changed however, and it was trivial to make it a good producer aswell.

Before i submit a patch however, I want to have this issue recorded and give everyone a chance to voice anything related.