* net_db.c: remove bogus "close" declaration.

	* net_db.c: remove bogus "close" declaration.
	(inet_aton declaration, scm_inet_aton, scm_inet_ntoa,
	scm_inet_netof, scm_lnaof, scm_inet_makeaddr, INADDR_ANY etc.):
	moved to socket.c.
	* net_db.h: declarations moved too.

	* socket.c (scm_htonl, scm_ntohl): use uint32_t instead of unsigned
	long.
	(ipv6_net_to_num, ipv6_num_to_net): new static procedures.
	(VALIDATE_INET6): new macro.
	(scm_inet_pton, scm_inet_ntop): new procedures, implementing
	inet-pton and inet-ntop.
	(scm_fill_sockaddr): use VALIDATE_INET6 and ipv6_num_to_net.
	(scm_addr_vector): use ipv6_net_to_num.