patch applied (cabal): Simplify parameters to defaultMain__

[Duncan Coutts]

Fri Nov 16 05:23:23 PST 2007  Duncan Coutts <duncan at haskell.org>
  * Simplify parameters to defaultMain__
  Don't use maybe, just have the callers pass the defaults instead.
  Eliminate the Maybe PackageDescription parameter and instead just have
  the called override the readDesc in the UserHooks.
  This simplifies defaultMainWorker too as it can always just use readDesc.

    M ./Distribution/Simple.hs -28 +22