patch applied (cabal-install): Add Hackage.LocalIndex module as an index of installed packages

[Duncan Coutts]

Fri Jan 18 13:59:53 PST 2008  Duncan Coutts <duncan at haskell.org>
  * Add Hackage.LocalIndex module as an index of installed packages
  Very much like the RepoIndex module but only holds package ids at the moment
   rather that full InstalledPackageInfo records that we'd really prefer.

    A ./Hackage/LocalIndex.hs
    M ./cabal-install.cabal +1