patch applied (cabal): Replace moduleToFilePath with findFileWithExtension

[Duncan Coutts]

Tue Feb  5 17:45:54 PST 2008  Duncan Coutts <duncan at haskell.org>
  * Replace moduleToFilePath with findFileWithExtension
  moduleToFilePath encouraged bad error handling and becuase it was specific
  to module names it made it hard to treat modules and main.hs files uniformly.
  This is one step towards using the same code paths for modules and main.hs
  files so that main.hs files always work properly with pre-processors etc.

    M ./Distribution/Simple/GHC.hs -8 +16
    M ./Distribution/Simple/Haddock.hs -6 +9
    M ./Distribution/Simple/Hugs.hs -8 +9
    M ./Distribution/Simple/NHC.hs -4 +6
    M ./Distribution/Simple/PreProcess.hs -10 +12
    M ./Distribution/Simple/SrcDist.hs -1 +1
    M ./Distribution/Simple/Utils.hs -44 +1