r600: workaround empty geom shader.

r600: workaround empty geom shader.

We need to emit at least one cut/emit in every
geometry shader, the easiest workaround it to
stick a single CUT at the top of each geom shader.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Cc: "10.6 11.0 11.1" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
(cherry picked from commit 4f347225752b48f3dc5a59a6be71fe78616252a7)
[Emil Velikov: squash trivial conflict]
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Conflicts:
	src/gallium/drivers/r600/r600_shader.c