xf86-video-modesetting: Changes to 'sh3224'

[Dave Airlie]

New branch 'sh3224' available with the following commits:
commit 911d4775b9a3e36d7deeb41bcdb99c4e4649d99d
Author: Dave Airlie <airlied at redhat.com>
Date:   Mon Jan 20 01:26:00 2014 -0500

    modesetting: 24bpp are too confusing, shadow our way out.
    
    So we have 2 places where gpus with 24bpp frontbuffers are still
    in use, cirrus (in qemu) and some early variants of the mgag200
    server chips.
    
    Currently we seem to get a lot of broken rendering in qt, mesa, gnome
    if we expose the frontbuffer as 24bpp, nobody seems to test this
    anymore upstream so client side apps are constantly broken, so lets
    just make -modesetting expose a 24/32 shadow frontbuffer, and use
    the shadow update hook to convert down to the actual 24bpp front,
    this might be slower, but its correct and really anyone that wants
    this already has enough problems.
    
    Signed-off-by: Dave Airlie <airlied at redhat.com>