Changes to ghc

Changes to ghc:
commit f5fa0dee87a0032aa73ab81141f39af87c2a324d
Author: Edward Z. Yang <ezyang@cs.stanford.edu>
Date:   Tue Jul 1 19:41:00 2014 +0100

    Backpack docs: Compilation, surface syntax, and package database

    Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>