Initialize {All}UserStartMenuDir and DesktopDir earlier.

Task-number: QTIFW-346

Change-Id: I641d6c2eb6b74f674b61ccf335885d4577dfcfe4
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>