aco: set has_color_exports with GPL
Signed-off-by:Rhys Perry <pendingchaos02@gmail.com> Reviewed-by:
Samuel Pitoiset <samuel.pitoiset@gmail.com> Fixes: 192486b7 ("aco/gfx11: export mrtz in discard early exit for non-color shaders") Part-of: <mesa/mesa!20937>