patch applied (cabal): Set the Cabal version when building via the fptools build system

[Sven Panne]

Sat Jan  6 07:28:14 PST 2007  sven.panne at aedion.de
  * Set the Cabal version when building via the fptools build system
  
  Without this patch, Cabal is effectively "version-less" and all .cabal
  files with a version requirement are unusable. Therefore I think that
  this patch (or at least something equivalent) should be pushed to the
  6.6.1 branch, too.

    M ./Makefile -1 +2