gallium: Add __DRIimageDriverExtension support to gallium
__DRIimageDriverExtension is used by GLX DRI3 and Wayland.
This patch is a rewrite of
http://lists.freedesktop.org/archives/mesa-dev/2014-May/060318.html
and
http://lists.freedesktop.org/archives/mesa-dev/2014-May/060317.html
Previous patches were:
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Axel Davy <axel.davy@ens.fr>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>