patch applied (packages/Cabal): No need to drop dist/installed-pkg-config after every build

[Ian Lynagh]

Wed May 27 13:45:00 PDT 2009  Duncan Coutts <duncan at haskell.org>
  * No need to drop dist/installed-pkg-config after every build
  We generate this file if necessary when registering.

    M ./Distribution/Simple.hs -8 +3

View patch online:
http://darcs.haskell.org/packages/Cabal/_darcs/patches/20090527204500-adfee-b49c5491271fb042b9cb2e7606c935dc95835828.gz