xwayland: use -listenfd if available

Xwayland's -listen option was deprecated in [1] in favor of -listenfd.

[1]: https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/593

include/xwayland/meson.build

@@ -1,11 +1,14 @@
+have_listenfd = false
 if xwayland.found()
 	xwayland_path = xwayland.get_pkgconfig_variable('xwayland')
+	have_listenfd = xwayland.get_pkgconfig_variable('have_listenfd') == 'true'
 else
 	xwayland_path = xwayland_prog.full_path()
 endif
 
 xwayland_config_data = configuration_data()
 xwayland_config_data.set_quoted('XWAYLAND_PATH', xwayland_path)
+xwayland_config_data.set10('HAVE_XWAYLAND_LISTENFD', have_listenfd)
 configure_file(
 	output: 'config.h',
 	configuration: xwayland_config_data,

xwayland/server.c

@@ -64,8 +64,13 @@ noreturn static void exec_xwayland(struct wlr_xwayland_server *server) {
 	char *argv[] = {
 		"Xwayland", NULL /* display, e.g. :1 */,
 		"-rootless", "-terminate", "-core",
+#if HAVE_XWAYLAND_LISTENFD
+		"-listenfd", NULL /* x_fd[0] */,
+		"-listenfd", NULL /* x_fd[1] */,
+#else
 		"-listen", NULL /* x_fd[0] */,
 		"-listen", NULL /* x_fd[1] */,
+#endif
 		"-wm", NULL /* wm_fd[1] */,
 		NULL,
 	};
@@ -91,7 +96,7 @@ noreturn static void exec_xwayland(struct wlr_xwayland_server *server) {
 	snprintf(wayland_socket_str, sizeof(wayland_socket_str), "%d", server->wl_fd[1]);
 	setenv("WAYLAND_SOCKET", wayland_socket_str, true);
 
-	wlr_log(WLR_INFO, "WAYLAND_SOCKET=%d Xwayland :%d -rootless -terminate -core -listen %d -listen %d -wm %d",
+	wlr_log(WLR_INFO, "WAYLAND_SOCKET=%d Xwayland :%d -rootless -terminate -core -listenfd %d -listenfd %d -wm %d",
 		server->wl_fd[1], server->display, server->x_fd[0],
 		server->x_fd[1], server->wm_fd[1]);