* fhandler_disk_file.cc (fhandler_base::fstat_by_handle): Drop

usage of path_conv::volser().
	(fhandler_base::fstat_by_name): Ditto.
	* ntdll.h (STATUS_NO_MEDIA_IN_DEVICE): Define.
	(STATUS_OBJECT_NAME_NOT_FOUND): Define.
	(FILE_REMOVABLE_MEDIA, FILE_READ_ONLY_DEVICE, FILE_FLOPPY_DISKETTE)
	(FILE_WRITE_ONCE_MEDIA, FILE_REMOTE_DEVICE, FILE_DEVICE_IS_MOUNTED)
	(FILE_VIRTUAL_VOLUME, FILE_AUTOGENERATED_DEVICE_NAME)
	FILE_DEVICE_SECURE_OPEN): Define Device Characteristics.
	(struct _FILE_FS_DEVICE_INFORMATION): Define.
	* path.cc (MAX_FS_INFO_CNT): Remove.
	(fsinfo): Remove.
	(fsinfo_cnt): Remove.
	(fs_info::update): Rewrite using native NT functions.  Drop fs_info
	cashing since it's incorrect.
	(path_conv::fillin): Use NtQueryInformationFile.  Drop setting serial
	number.
	(path_conv::check): Accommodate new fs_info::update parameters.
	(fillout_mntent): Ditto.
	* path.h (fs_info): Drop serial, has_ea and drive_type status
	flags.
	(fs_info::update): Declare with new parameters.
	(path_conf::drive_type): Remove.
	(path_conf::fs_has_ea): Remove.
	(path_conf::volser): Remove.

winsup/cygwin/fhandler_disk_file.cc

@@ -279,7 +279,7 @@ fhandler_base::fstat_by_handle (struct __stat64 *buf)
     {
       debug_printf ("%u = NtQueryVolumeInformationFile)",
 		    RtlNtStatusToDosError (status));
-      pfvi->VolumeSerialNumber = pc.volser ();
+      pfvi->VolumeSerialNumber = 0;
     }
   status = NtQueryInformationFile (get_handle (), &io, pfai, fai_size,
 				   FileAllInformation);
@@ -371,7 +371,7 @@ fhandler_base::fstat_by_name (struct __stat64 *buf)
     {
       debug_printf ("%u = NtQueryVolumeInformationFile)",
 		    RtlNtStatusToDosError (status));
-      pfvi->VolumeSerialNumber = pc.volser ();
+      pfvi->VolumeSerialNumber = 0;
     }
   NtClose (dir);
   /* If the change time is 0, it's a file system which doesn't
@@ -403,7 +403,7 @@ too_bad:
 		       *(FILETIME *) &ft,
 		       *(FILETIME *) &ft,
 		       *(FILETIME *) &ft,
-		       pc.volser (),
+		       0,
 		       0ULL,
 		       -1LL,
 		       0ULL,