fixed a few functions I've missed

Signed-off-by: Michael Kaufmann <d00p@froxlor.org>

install/updates/preconfig.php

@@ -47,7 +47,7 @@ function getPreConfig($current_version, $current_db_version)
 
 function versionInUpdate($current_version, $version_to_check)
 {
-	if (! isFroxlor()) {
+	if (! \Froxlor\Froxlor::isFroxlor()) {
 		return true;
 	}