Changes to ghc

Changes to ghc:
commit 723095b0e4c5838c7eefd757af56ab2a7c614801
Author: Edward Z. Yang <ezyang@cs.stanford.edu>
Date:   Thu May 29 20:05:51 2014 -0700

    Per-capability nursery weak pointer lists, fixes #9075

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