Updated restart of libreoffice for systemd

bigbluebutton-config/cron.daily/bigbluebutton

@@ -120,5 +120,5 @@ find /tmp -name "*.pfb" -mtime +$history -delete
 # If there are no users currently logged in, restart libreoffice to clear its memory usage
 #
 if [[ $(netstat -ant | egrep ":1935\ " | egrep -v ":::|0.0.0.0"  | wc | awk '{print $1}') == 0 ]]; then
-  service libreoffice restart
+  systemctl restart libreoffice.service
 fi