Add version to ghc dependency

haddock-ghc.cabal

@@ -8,7 +8,7 @@ maintainer: David Waern <davve@dtek.chalmers.se>
 stability: stable
 homepage: http://www.haskell.org/haddock/
 synopsis: Haddock is a documentation-generation tool for Haskell libraries
-build-depends: base>=1.0, haskell98>=1.0, mtl>=1.0, ghc, network>=1.0, Cabal, FilePath>=0.11
+build-depends: base>=1.0, haskell98>=1.0, mtl>=1.0, ghc>=6.7, Cabal, FilePath>=0.11, network>=1.0
 extensions: CPP, PatternGuards
 ghc-options: -fglasgow-exts
 hs-source-dirs: src