missing global in filter.inc

src/etc/inc/filter.inc

@@ -320,6 +320,8 @@ function filter_pflog_start()
 
 function filter_configure()
 {
+    global $config;
+
     /*
      * NOTE: Check here for bootup status since this should not be triggered during bootup.
      *   The reason is that rc.bootup calls filter_configure_sync directly which does this too.