Add a repaint completion signal for weston output

This signal is particular needed for externally compositing surfaces.
An external renderer can do buffer swap only after render completion is
signalled. It is possible that in the render completion signal
callback external renderer can render, buffer swap and schedule next
repaint. Next repaint won't be scheduled if frame_signal is used
and hence a new signal is added.

Signed-off-by: harsha.mm <harsha.manjulamallikarjun@in.bosch.com>

libweston/compositor.c

@@ -2327,6 +2327,9 @@ weston_output_repaint(struct weston_output *output)
 		animation->frame(animation, output, output->frame_time);
 	}
 
+	/*Signal hinting that the rendering for this output is complete*/
+	wl_signal_emit(&output->render_complete_signal, output);
+
 	TL_POINT("core_repaint_posted", TLP_OUTPUT(output), TLP_END);
 
 	return r;
@@ -4634,6 +4637,7 @@ weston_output_enable(struct weston_output *output)
 
 	wl_signal_init(&output->frame_signal);
 	wl_signal_init(&output->frame_finish_signal);
+	wl_signal_init(&output->render_complete_signal);
 	wl_signal_init(&output->destroy_signal);
 	wl_list_init(&output->animation_list);
 	wl_list_init(&output->resource_list);

libweston/compositor.h

@@ -177,6 +177,7 @@ struct weston_output {
 	int dirty;
 	struct wl_signal frame_signal;
 	struct wl_signal frame_finish_signal;
+	struct wl_signal render_complete_signal;
 	struct wl_signal destroy_signal;
 	int move_x, move_y;
 	uint32_t frame_time; /* presentation timestamp in milliseconds */