Fix status check in init script. Closes: #747146

Thanks Marc Matters.

debian/pptpd.init

@@ -76,7 +76,7 @@ stop)
     esac
     ;;
 status)
-    status_of_proc "$PIDFILE" "$DAEMON" "$NAME" && exit 0 || exit $?
+    status_of_proc -p "$PIDFILE" "$DAEMON" "$NAME" && exit 0 || exit $?
     ;;
 restart|force-reload)
     log_daemon_msg "Restarting $DESC" "$NAME"