compositor: drop surface precommit event

This is unused.

include/wlr/types/wlr_compositor.h

@@ -174,7 +174,6 @@ struct wlr_surface {
 
 	struct {
 		struct wl_signal client_commit;
-		struct wl_signal precommit; // const struct wlr_surface_state *
 		struct wl_signal commit;
 
 		/**

types/wlr_compositor.c

@@ -427,8 +427,6 @@ static void surface_commit_state(struct wlr_surface *surface,
 		struct wlr_surface_state *next) {
 	assert(next->cached_state_locks == 0);
 
-	wl_signal_emit_mutable(&surface->events.precommit, next);
-
 	bool invalid_buffer = next->committed & WLR_SURFACE_STATE_BUFFER;
 
 	if (invalid_buffer && next->buffer == NULL) {
@@ -691,7 +689,6 @@ static struct wlr_surface *surface_create(struct wl_client *client,
 	surface->pending.seq = 1;
 
 	wl_signal_init(&surface->events.client_commit);
-	wl_signal_init(&surface->events.precommit);
 	wl_signal_init(&surface->events.commit);
 	wl_signal_init(&surface->events.map);
 	wl_signal_init(&surface->events.unmap);