patch applied (ghc-6.12/packages/Cabal): Make the datadir follow the $prefix on Windows

[Ian Lynagh]

Mon Dec 28 08:50:56 PST 2009  Duncan Coutts <duncan at haskell.org>
  * Make the datadir follow the $prefix on Windows
  This is slightly experimental, we'll see how it goes. See ticket #466.

    M ./Distribution/Simple/InstallDirs.hs -5 +2