Changes to ghc ghc-prim

Changes to ghc:
commit 41ab58415224b7fa27cfc27846d4b56aad3e1949
Author: Joachim Breitner <mail@joachim-breitner.de>
Date:   Fri Mar 14 09:23:15 2014 +0100

    Remove unused gHC_COERCIBLE

Changes to ghc-prim:
commit db4f5e5245d5b24a8f0a06a85ded89c6124fb4c7
Author: Joachim Breitner <mail@joachim-breitner.de>
Date:   Fri Mar 14 09:26:12 2014 +0100

    Update Coercible docs due to Safe Haskell adjustment

    This should go with [59722295bb8da8f01d37356fbed6aef7321a8195/ghc], see
    bug #8826.