* fhandler.h (fhandler_base::fstat_helper): Declare with additional

	* fhandler.h (fhandler_base::fstat_helper): Declare with additional
	dwVolumeSerialNumber argument.  Drop default values for last three
	arguments.
	* fhandler_disk_file.cc (fhandler_base::fstat_by_handle): Pass
	dwVolumeSerialNumber from GetFileInformationByHandle to fstat_helper.
	(fhandler_base::fstat_by_name): Pass pc.volser () to fstat_helper.
	Accomodate dropping default values for last three arguments of
	fstat_helper.
	(fhandler_base::fstat_helper): Add dwVolumeSerialNumber argument.
	Use for st_dev member unless 0 in which case pc.volser () is used.