Changes to ghc

Changes to ghc:
commit 431da1a6a8db6a3f3065fe1e1590790f736309ce
Author: Christiaan Baaij <christiaan.baaij@gmail.com>
Date:   Mon Apr 28 12:13:11 2014 +0200

    Mention TH pattern splices in 7.8.1 release notes