qmljs: lookup libraries in the correct place

This lead some libraries to be “lost”, typically QtQuick

Change-Id: I44e8fd12f53ce1371a2d4bd094fe5b67cad30676
Reviewed-by: Tim Jenssen <tim.jenssen@theqtcompany.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>