commands: port lxc_get_tty_fd() to new helpers

src/lxc/commands.c

@@ -1125,13 +1125,11 @@ int lxc_cmd_get_tty_fd(const char *name, int *ttynum, int *fd, const char *lxcpa
 {
 	__do_free struct lxc_cmd_tty_rsp_data *rspdata = NULL;
 	bool stopped = false;
-	struct lxc_cmd_rr cmd = {
-		.req = {
-			.cmd	= LXC_CMD_GET_TTY_FD,
-			.data	= INT_TO_PTR(*ttynum),
-		},
-	};
 	int ret;
+	struct lxc_cmd_rr cmd;
+
+	lxc_cmd_init(&cmd, LXC_CMD_GET_TTY_FD);
+	lxc_cmd_data(&cmd, ENCODE_INTO_PTR_LEN, INT_TO_PTR(*ttynum));
 
 	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
 	if (ret < 0)