libweston-desktop: Drop (wrongly named) new_buffer in committed

Instead we store the buffer move and just use it when the signal is
fired.

Signed-off-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
diff --git a/libweston-desktop/internal.h b/libweston-desktop/internal.h
index 21181a6..a9c974b 100644
--- a/libweston-desktop/internal.h
+++ b/libweston-desktop/internal.h
@@ -96,7 +96,7 @@
 	void (*set_size)(struct weston_desktop_surface *surface,
 			 void *user_data, int32_t width, int32_t height);
 	void (*committed)(struct weston_desktop_surface *surface, void *user_data,
-		          bool new_buffer, int32_t sx, int32_t sy);
+		          int32_t sx, int32_t sy);
 	void (*update_position)(struct weston_desktop_surface *surface,
 				void *user_data);
 	void (*ping)(struct weston_desktop_surface *surface, uint32_t serial,