Stop changelog feed importing class that was already imported

sections/feeds/index.php

     $Feed->channel('Gazelle Change Log', 'RSS feed for Gazelle\'s changelog.');
     if (!$Changelog = $Cache->get_value('changelog')) {
       require(SERVER_ROOT.'/classes/mysql.class.php');
-      require(SERVER_ROOT.'/classes/misc.class.php');
+      require_once(SERVER_ROOT.'/classes/misc.class.php');
 
       $DB = NEW DB_MYSQL;
       $DB->query("