need a newer happy than is in stable
newer alex also needed on stable
enable improved hsc2hs cross-compilation support and configure cross-compilation support

Found these options in the ghc-ios cabal wrapper, hopefully it will solve
issues cross-compiling packages that use configure and/or hsc2hs.
fix path to cross ghc packagedb

The directory is something like this with current ghc builds:
arm-unknown-linux-androideabi-ghc-7.7.20130921
typo
install a new enough cabal to get the cross-compilation fixes

Relevant fix:

commit 9f374ab45e62924506b992db9157c970c7259a03
Author: Stephen Blackheath <stephen.blackheath@ipwnstudios.com>
Date:   Thu Aug 29 13:09:18 2013 +1200

    Give the xxx_HOST_OS and xxx_HOST_ARCH options that were probed from ghc's target
    platform, rather than assuming HOST == BUILD. This fixes things for cross compiling.