* fhandler_registry.cc (DEFAULT_VALUE_NAME): Remove constant.

	* fhandler_registry.cc (DEFAULT_VALUE_NAME): Remove constant.
	(encode_regname): Encode empty (default) name to "@".
	Encode "@" to "%40".  Change error return to -1.
	(decode_regname): Decode "@" to empty name.  Decode "%40" to "@".
	(fhandler_registry::exists): Skip check for keys if name is empty.
	Remove check for DEFAULT_VALUE_NAME, now handled by decode_regname ().
	(fhandler_registry::readdir): Remove check for empty name, now
	handled by encode_regname ().
	(fhandler_registry::open): Remove check for DEFAULT_VALUE_NAME.
	(fhandler_registry::open_key): Fail with ENOENT if key name is empty.