logs: fix Call to undefined function system_syslogd_start()

(cherry picked from commit 78ee8848)

src/www/diag_logs_filter_summary.php

@@ -29,6 +29,7 @@
 
 require_once("guiconfig.inc");
 require_once("filter_log.inc");
+require_once("system.inc");
 require_once("interfaces.inc");
 
 $filter_logfile = '/var/log/filter.log';