xwayland/server: add ready flag

Allows one to check whether the server is currently ready.

include/wlr/xwayland/server.h

@@ -27,6 +27,7 @@ struct wlr_xwayland_server {
 	struct wl_client *client;
 	struct wl_event_source *pipe_source;
 	int wm_fd[2], wl_fd[2];
+	bool ready;
 
 	time_t server_start;
 

xwayland/server.c

@@ -275,6 +275,7 @@ static int xserver_handle_ready(int fd, uint32_t mask, void *data) {
 	close(fd);
 	wl_event_source_remove(server->pipe_source);
 	server->pipe_source = NULL;
+	server->ready = true;
 
 	struct wlr_xwayland_server_ready_event event = {
 		.server = server,