(legacy) missing dependency, fixes PHP Fatal error: Call to undefined...

(legacy) missing dependency, fixes PHP Fatal error:  Call to undefined function is_private_ip() in /usr/local/etc/inc/services.inc on line 1750

(cherry picked from commit 394ad989)

src/www/services_rfc2136_edit.php

@@ -30,6 +30,7 @@
 require_once("guiconfig.inc");
 require_once("services.inc");
 require_once("interfaces.inc");
+require_once("pfsense-utils.inc");
 
 if (!isset($config['dnsupdates']['dnsupdate'])) {
 	$config['dnsupdates']['dnsupdate'] = array();