hackport-0.5.1: cabal/update-cabal-files.sh

#!/bin/sh
(cd Cabal; misc/gen-extra-source-files.hs Cabal.cabal)
(cd cabal-testsuite; ../Cabal/misc/gen-extra-source-files.hs cabal-testsuite.cabal)
(cd cabal-install; ../Cabal/misc/gen-extra-source-files.hs cabal-install.cabal)