Changes to ghc

Changes to ghc:
commit c63a465011b99eeafbb957074e54c2e6bbf751d9
Author: Owen Stephens <owen@owenstephens.co.uk>
Date:   Thu Apr 10 17:44:11 2014 +0100

    Subsume NullaryTypeClasses by MultiParamTypeClasses (#8993)

    MPTC now also handles the nullary case