Add IPv6 support.

Add IPv6 support.

configure.in: Check for struct sockaddr.sa_len and struct addrinfo.
    Also check for freeaddrinfo, getaddrinfo and getnameinfo.

src/common.h: Define irc_in_addr and macros to operate on it.  Declare
    irc_ntop(), irc_ntop_mask(), irc_pton(), irc_check_mask() and
    irc_ntoa().  Remove declaration for parse_ipmask() and undefine
    INADDR_NONE, INADDR_LOOPBACK and MATCH_IPMASK().

src/compat.h (struct addrinfo): Define if it and some flags if not
    defined by the system.
  (getaddrinfo): Declare if necessary.
  (getnameinfo): Likewise.
  (freeaddrinfo): Likewise.

src/compat.c (memcpy): Do not try to fall back onto bcopy.
  (getaddrinfo): Define if it is not defined by the system.
  (freeaddrinfo): Likewise.

src/gline.c (gline_alternate_target): Gut in preparation of a
    necessary rewrite.  Blah.

src/hash.h (struct userNode): Change type of ip field.

src/ioset.c (ioset_connect): Update to support non-IPv4 protocols.

src/main.c (uplink_insert): Update to support non-IPv4 protocols.

src/mod-snoop.c (snoop_new_user): Use irc_ntoa() instead of inet_ntoa().

src/mod-sockcheck.c (sockcheck_cache_info): Update address field type
    and length of hostname field.
  (sockcheck_conf): Update type of local_addr.
  (sockcheck_issue_gline): Update to use irc_ntop().
  (expand_var): Get client IPv4 address from its new place.
  (sockcheck_decide): Do not print the IP twice.
  (sockcheck_begin_test): Remove unnecessary typecast.
  (sockcheck_start_client): Do not print the IP twice.
  (sockcheck_queue_address): Use irc_in_addr_t and irc_ntoa() to form
    the target hostname.
  (cmd_hostscan): Update manipulation functions to use new macros and
    functions for irc_in_addr_t.
  (cmd_clearhost): Likewise.
  (sockcheck_new_user): Likewise.
  (sockcheck_read_conf): Use getaddrinfo() instead of IPv4-only
    functions.

src/nickserv.c (cmd_register): Use newer validity checks for IP.

src/opserv.c (IDENT_DATA): Use irc_ntoa() instead of inet_ntoa().
  (struct opservDiscrim): Update ip_mask and ip_mask_bits type.
  (cmd_whois): Use irc_ntoa() instead of inet_ntoa().
  (opserv_new_user_check): Use irc_ntop() instead of inet_ntoa() and
    update to newer validity check macros.
  (opserv_user_cleanup): Use irc_ntop() instead of inet_ntoa().
  (cmd_addtrust): Update to irc_in_addr_t and its functions.
  (foreach_matching_user): Use irc_pton() instead of the mess that
    existed before.
  (opserv_discrim_create): Use irc_pton() instead of parse_ipmask().
  (discrim_match): Use irc_check_mask() instead of MATCH_IPMASK(), and
    remove ip_mask_str check.
  (opserv_discrim_search): Decide whether an IP match is fully
    qualified based on ip_mask_bits instead of ip_mask_str.
  (trace_domains_func): Add IPv6 support.
  (opserv_staff_alert): Update to new IP validity check macro.

src/proto.h (struct uplinkNode): Fix type of bind_addr field.

src/proto-bahamut.c (AddUser): Use irc_in_addr_t.
  (AddService): Default to an all-zero IP instead of loopback.
  (AddClone): Likewise.
  (irc_user): Use new layout for IPv4 in irc_in_addr_t.
  (cmd_nick): Likewise.

src/proto-common.c (create_socket_client): Remove unnecessary
    typecast.
  (generate_hostmask): Update to use irc_in_addr_t and support
    functions instead of IPv4-specific things.

src/proto-p10.c (irc_p10_pton): New function.
  (irc_p10_ntop): New function.
  (irc_user): Use irc_p10_ntop().
  (AddClone): Use irc_p10_pton().

src/tools.c (ctype): New array holding values of characters as hex.
  (irc_ntop): New function.
  (irc_ntop_mask): New function.
  (irc_pton_ip4): New helper function.
  (irc_pton): New function.
  (irc_ntoa): New function.
  (irc_check_mask): New function.
  (user_matches_glob): Use irc_ntoa() instead of inet_ntoa().
  (parse_ipmask): Delete this function.
git-archimport-id: srvx@srvx.net--2005-srvx/srvx--devo--1.3--patch-28