patch applied (ghc): move and generalize an instance (#1405)

[Simon Peyton Jones]

Wed Dec 26 09:19:13 PST 2007  Isaac Dupree <id at isaac.cedarswampstudios.org>
  * move and generalize an instance (#1405)
  UserOfLocalRegs (ZLast Last) isn't Haskell98, but it was just as
  good an instance to be UserOfLocalRegs a => UserOfLocalRegs (ZLast a)

    M ./compiler/cmm/ZipCfg.hs +10
    M ./compiler/cmm/ZipCfgCmmRep.hs -4