Fix the error message when execute ldpd with --enable-tcp-zebra

- If we use the option "--enable-tcp-zebra " to configure, the zclient will use the tcp socket instead of unix domain socket.
- The ldpd will pass the "-z path" options to `frr_opt` and that will execute zclient_serv_path_set to check the domain socket.
- Add the define to ldpd, if the "HAVE_TCP_ZEBRA" has been define, don't pass the "-z path" to `frr_opt`.

Signed-off-by: Hung-Weic Chiu <sppsorrg@gmail.com>

ldpd/ldpd.c

@@ -500,8 +500,11 @@ start_child(enum ldpd_process p, char *argv0, int fd_async, int fd_sync,
 		argv[argc++] = (char *)ctl_sock_custom_path;
 	}
 	/* zclient serv path */
+#ifdef HAVE_TCP_ZEBRA
+#else
 	argv[argc++] = (char *)"-z";
 	argv[argc++] = (char *)zclient_serv_path_get();
+#endif
 	/* instance */
 	if (instance) {
 		argv[argc++] = (char *)"-n";