patch applied (cabal): Less confusing haddock command output when there are no libs in the package

[Duncan Coutts]

Fri Aug  3 18:31:33 PDT 2007  Duncan Coutts <duncan at haskell.org>
  * Less confusing haddock command output when there are no libs in the package
  It says:
  > No documentation was generated as this package does not contain a library.
  > Perhaps you want to use the haddock command with the --executables flag.

    M ./Distribution/Simple/Haddock.hs +6