Changes to ghc

Changes to ghc:
commit 61cce9116ac1a927632979e56dfa9754c69d2441
Author: Edward Z. Yang <ezyang@cs.stanford.edu>
Date:   Thu Jul 10 17:07:18 2014 +0100

    [backpack] Rework definite package compilation

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