lib: correctly handle v6 in addresses directives

previously, if you tried to add an IPv6 address using one of the
directives Dir Address, FD Address or SD Address, it would listen on
0.0.0.0. This patch sees if the string looks like an IPv6 address and
adds it correctly leading to a less surprising behaviour.

core/src/lib/res.cc

@@ -1318,7 +1318,8 @@ void ConfigurationParser::StoreAddressesAddress(LEX* lc,
 
   if (pass == 1
       && !AddAddress(GetItemVariablePointer<dlist<IPADDR>**>(*item),
-                     IPADDR::R_SINGLE_ADDR, htons(port), AF_INET, lc->str, 0,
+                     IPADDR::R_SINGLE_ADDR, htons(port),
+                     strchr(lc->str, ':') ? AF_INET6 : AF_INET, lc->str, 0,
                      errmsg, sizeof(errmsg))) {
     scan_err2(lc, _("can't add port (%s) to (%s)"), lc->str, errmsg);
   }