Changes to ghc

Changes to ghc:
commit 306d255de6c33a2430822524bc81d07ec5c1e456
Author: Joachim Breitner <mail@joachim-breitner.de>
Date:   Fri Mar 14 18:25:07 2014 +0100

    Call Arity: Never eta-expand thunks in recursive groups

    Even if the recursion is a nice tail-call only recusion, we'd stil be
    calling the thunk multiple times and eta-expansion would be wrong.
    Includes a [Note].

    (Also shows the disadvantage of unit tests: They had the same bug.)