patch applied (packages/base): the " unknown" types are no longer required

[Simon Marlow]

Thu Apr 26 06:59:31 PDT 2007  Simon Marlow <simonmar at microsoft.com>
  * the "unknown" types are no longer required

    M ./GHC/Base.lhs -6
    M ./GHC/Exts.hs -1 +1
    M ./GHC/Show.lhs -28