patch applied (cabal): Add setup register --gen-pkg-config flag for distros that want that.

[Duncan Coutts]

Sat Aug  4 04:55:12 PDT 2007  Duncan Coutts <duncan at haskell.org>
  * Add setup register --gen-pkg-config flag for distros that want that.
  It generates the actual file to be passed to the compiler's package program.
  This is obviously compiler-specific.

    M ./Distribution/Setup.hs -1 +13
    M ./Distribution/Simple.hs -2 +2
    M ./Distribution/Simple/Register.hs -18 +30