Changes to ghc

Changes to ghc:
commit 7b04d35a87f1ee2904579a916ef1a6b0aa6fc7b8
Author: Herbert Valerio Riedel <hvr@gnu.org>
Date:   Sat Apr 19 13:56:36 2014 +0200

    Weaken constraints on Data.Complex functions

    The RealFloat data type context was dropped from Data.Complex some time
    ago (see ea280135dd888ac41d8804a9e37e358180cf13ac). However, the rest of
    the API in that module was left as-is even though many of the accessors
    in that module would work with much more general types now.

    This change simplifies the signatures of the functions above, which in
    the current API all unnecessarily take a RealFloat constraint that they
    don't use (and which may cause to pass around superflous type-class
    dictionaries):

        realPart  :: Complex a -> a
        imagPart  :: Complex a -> a
        conjugate :: Num a => Complex a -> Complex a
        mkPolar   :: Floating a => a -> a -> Complex a
        cis       :: Floating a => a -> Complex a

    This was originally proposed by Edward Kmett in

      http://www.haskell.org/pipermail/libraries/2014-March/022358.html

    Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>