Changes to ghc

Changes to ghc:
commit e3938f3adac0093b23694fd347774244ce121478
Author: Edward Z. Yang <ezyang@cs.stanford.edu>
Date:   Sat Apr 12 23:02:13 2014 -0700

    Fix linked list manipulation code (buggy on consecutive deletion)

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