Qnx: Properly set Qt environment on device

Task-number: QTCREATORBUG-12171
Change-Id: I8adb7398991cf093771b561e4711b38df8aa0e27
Reviewed-by: Sergio Ahumada <sahumada@blackberry.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>