fix random crash while accessing arguments

  The problem is that QCoreAppliction changes these values in some cases.
  (Most often crash was when XCB was trying to get the qApp->arguments())

Change-Id: I41086f662dbead854864a29b2566355c6360b011
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
Reviewed-by: Karsten Heimrich <karsten.heimrich@digia.com>