patch applied (ghc-6.6/ghc): expand $topdir in the output of ' ghc-pkg field'

[Ian Lynagh]

Tue Jan  9 09:00:19 PST 2007  Simon Marlow <simonmar at microsoft.com>
  * expand $topdir in the output of 'ghc-pkg field'
  this fixed #937, and gets us further towards 'setup haddock' working
  for Cabal on Windows.

    M ./utils/ghc-pkg/Main.hs -1 +28