patch applied (cabal): delete removePreprocessed function, it's unused except for cleaning jhc files

[Duncan Coutts]

Sat Jan 26 15:02:56 PST 2008  Duncan Coutts <duncan at haskell.org>
  * delete removePreprocessed function, it's unused except for cleaning jhc files
  and jhc should just be putting its generated files under dist/ anyway.
  The latter issue is filed as bug #219.

    M ./Distribution/Simple.hs -14
    M ./Distribution/Simple/PreProcess.hs -28