patch applied (cabal-branches/cabal-1.2): Fix pre-processing for executables

[Ian Lynagh]

Sat Sep 22 03:54:14 PDT 2007  Duncan Coutts <duncan at haskell.org>
  * Fix pre-processing for executables
  The pre-processed files should go into the exe's build dir, not the
  lib's build dir. Also pre-process main modules, fixing bug #14.

    M ./Distribution/Simple/GHC.hs -1 +1
    M ./Distribution/Simple/PreProcess.hs -2 +7