Changes to ghc(2)

Changes to ghc:
commit 9c9bb00343c2ab4c985bf248b576106ea8fa5a3d
Author: Johan Tibell <johan.tibell@gmail.com>
Date:   Mon Mar 10 18:59:21 2014 +0100

    Fix copy-paste error in build system comment

commit ddf79ebf69fe4a6e69d69d451a6040a53b1ea12c
Author: Johan Tibell <johan.tibell@gmail.com>
Date:   Mon Mar 10 18:54:47 2014 +0100

    Add "bench" build flavour to build system

    This build generates the same code as the "perf" build and is thus
    good for compiling benchmarks and inspecting the generated
    code. However, it compiles the stage2 compiler faster at the expense
    of compiler user programs more slowly.