CUPS Remote Printers do not set page sizes correctly

In QCupsPrintEnginePrivate::setPaperSize() if the call to cups.currentPPD() fails then no fall-back is performed and the previous page metrics are retained which is inconsistent. This usually occurs for network printers that may not return a PPD. Need to code a fall-back using standard page dimensions, and investigate why network printer doesn't return a PPD.