Changes to ghc

Changes to ghc:
commit 5bdbd510a78f0c17d702fa9399cc0501cfd00fac
Author: Joachim Breitner <mail@joachim-breitner.de>
Date:   Mon Jun 9 20:55:22 2014 +0200

    Make Ptr's parameter phantom

    and implement castPtr with coerce, which gives
        12% less allocation in reverse-complem
        7.3% less allocation in fasta.
        Binary sizes fell 0.1%.
    as reported and discussed in #9163.