window: Run deferred tasks before blocking for initial iteration

The first iteration of the while loop wouldn't run the deferred tasks
before blocking in epoll_wait().  Move things around so we do.

clients/window.c

@@ -2998,26 +2998,26 @@ display_run(struct display *display)
 
 	display->running = 1;
 	while (1) {
-		while (display->mask & WL_DISPLAY_WRITABLE)
-			wl_display_iterate(display->display,
-					   WL_DISPLAY_WRITABLE);
+		wl_display_flush(display->display);
+
+		while (!wl_list_empty(&display->deferred_list)) {
+			task = container_of(display->deferred_list.next,
+					    struct task, link);
+			wl_list_remove(&task->link);
+			task->run(task, 0);
+		}
 
 		if (!display->running)
 			break;
 
+		wl_display_flush(display->display);
+
 		count = epoll_wait(display->epoll_fd,
 				   ep, ARRAY_LENGTH(ep), -1);
 		for (i = 0; i < count; i++) {
 			task = ep[i].data.ptr;
 			task->run(task, ep[i].events);
 		}
-
-		while (!wl_list_empty(&display->deferred_list)) {
-			task = container_of(display->deferred_list.next,
-					    struct task, link);
-			wl_list_remove(&task->link);
-			task->run(task, 0);
-		}
 	}
 }