Changes to ghc-prim

Changes to ghc-prim:
commit a3b0a06a2bbe37122f1a3d5e20926bc30f5656d1
Author: Herbert Valerio Riedel <hvr@gnu.org>
Date:   Sat Mar 1 11:05:45 2014 +0100

    Add Since-annotation to `Coercible`

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