patch applied (packages/Cabal): don' t check cabal-version during parsing, it doesn' t work

[Simon Marlow]

Fri Mar  3 07:55:00 PST 2006  Simon Marlow <simonmar at microsoft.com>
  * don't check cabal-version during parsing, it doesn't work
  because parsers are evaluated multiple times due to backtracking.

    M ./Distribution/PackageDescription.hs -6 +1