* mount.cc (struct opt): Add "dos" and "ihash" options.

	* mount.cc (struct opt): Add "dos" and "ihash" options.
	(fillout_mntent): Ditto.
	* path.cc (path_conv::get_nt_native_path): Use path_conv's
	has_dos_filenames_only method.
	(path_conv::check): Add PATH_IHASH flag if FS has unreliable inode
	numbers.
	(symlink_info::check_shortcut): Or symlink flags to pflags.
	(symlink_info::check_sysfile): Ditto.  Change test accordingly.
	(symlink_info::check_reparse_point): Ditto.
	(symlink_info::check_nfs_symlink): Ditto.
	(symlink_info::check): Check PATH_DOS flag in call to get_nt_native_path
	to utilize mount flag.  Ditto in test for potential restarting.  Set
	PATH_DOS if FS only allows DOS filename rules.
	* path.h (enum path_types): Add PATH_DOS and PATH_IHASH.
	(path_conv::hasgood_inode): Check PATH_IHASH instead of
	fs.hasgood_inode.
	(path_conv::has_dos_filenames_only): New method.
	* include/sys/mount.h (MOUNT_DOS): New mount flag.
	(MOUNT_IHASH): Ditto.