Changes to ghc(3)

Changes to ghc:
commit da66a8dff05f656cb379edf61827af426e1b05e7
Author: Joachim Breitner <mail@joachim-breitner.de>
Date:   Mon Jan 20 10:31:45 2014 +0000

    Test case for #T7619

    (artificial test cases are so nice: 90.7% improvement!)

commit 0c578870d5a65b496cb57b260cd83d71db50f3b3
Author: Joachim Breitner <mail@joachim-breitner.de>
Date:   Mon Jan 20 10:26:13 2014 +0000

    Simplify doCorePass

commit 2bb19fad1d809dda37011f442b0fd561aea045b6
Author: Joachim Breitner <mail@joachim-breitner.de>
Date:   Fri Jan 17 17:31:53 2014 +0000

    Make worker-wrapper unbox data families

    by passing the FamInstEnvs all the way down. This closes #7619.