* fhandler_disk_file.cc (fhandler_base::fstat_by_name): Check for

	* fhandler_disk_file.cc (fhandler_base::fstat_by_name): Check for
	file systems incapable of handling FileIdBothDirectoryInformation
	correctly.
	(fhandler_disk_file::opendir): Ditto.
	* path.cc (fs_info::update): Always clear at the start.
	Rearrange to make certain tests only on non-Samba, non-NFS remote
	drives.
	Add test for file systems known to be incapable of handling
	FileIdBothDirectoryInformation correctly.  Right now that's just
	"UNIXFS".
	* path.h (struct fs_info): Add has_buggy_fileid_dirinfo flag and
	accessor methods.
	(class path_conv): Add has_buggy_fileid_dirinfo method.