darcs patch: fix failure to compile with cabal included with ghc 6.6

I'm not sure if this is sufficient, or even a good idea, but removing this type signature makes Setup.hs able to run on my system with an older cabal. David Wed May 16 09:18:47 PDT 2007 David Roundy <droundy@darcs.net> * fix failure to compile with cabal included with ghc 6.6