patch applied (cabal): Let sdist command run the preprocessors itself. This way we don't

[Ian Lynagh]

Sat Jul 28 15:12:37 PDT 2007  Thomas Schilling <nominolo at gmail.com>
  * Let sdist command run the preprocessors itself.  This way we don't
  have to put stuff into the source tree.

    M ./Distribution/Simple/SrcDist.hs -3 +13