darcs patch : Add --program-prefix and --program-suffix options to configure (#208)

Attached is a patch that should resolve ticket #208. I wanted to "contribute" to Haskell in some way and an easy task seemed like a good place to start. I would have spoke up about my intent, but I wasn't sure how easy an "Easy Ticket" was. Yep, they're pretty easy! I have just joined the cabal-devel list, so if you have comments on the code feel free to speak up. Peter