tls: remove confusing error message when trying to print socket for <default> server

> CRITICAL: <core> [core/ip_addr.c:232]: ip_addr2sbuf(): unknown address family 0
> NOTICE: tls [tls_domain.c:1176]: ksr_tls_fix_domain(): registered server_name callback handler for socket [:0], server_name='<default>' ...

(cherry picked from commit 87c8290ab934fd27f8baebabaf66d1fb4168ba72)
(cherry picked from commit be76a51422df3294c533accae1b6a621ee9d3a7d)

src/modules/tls/tls_domain.c

@@ -1155,14 +1155,14 @@ static int ksr_tls_fix_domain(tls_domain_t *d, tls_domain_t *def)
 					   d->ctx[i], tls_server_name_cb)) {
 				LM_ERR("register server_name callback handler for socket "
 					   "[%s:%d], server_name='%s' failed for proc %d\n",
-						ip_addr2a(&d->ip), d->port,
+						(d->ip.af > 0) ? ip_addr2a(&d->ip) : "0.0.0.0", d->port,
 						(d->server_name.s) ? d->server_name.s : "<default>", i);
 				return -1;
 			}
 			if(!SSL_CTX_set_tlsext_servername_arg(d->ctx[i], d)) {
 				LM_ERR("register server_name callback handler data for socket "
 					   "[%s:%d], server_name='%s' failed for proc %d\n",
-						ip_addr2a(&d->ip), d->port,
+						(d->ip.af > 0) ? ip_addr2a(&d->ip) : "0.0.0.0", d->port,
 						(d->server_name.s) ? d->server_name.s : "<default>", i);
 				return -1;
 			}
@@ -1175,7 +1175,7 @@ static int ksr_tls_fix_domain(tls_domain_t *d, tls_domain_t *def)
 			&& (d->server_name.len > 0 || (d->type & TLS_DOMAIN_DEF))) {
 		LM_NOTICE("registered server_name callback handler for socket "
 				  "[%s:%d], server_name='%s' ...\n",
-				ip_addr2a(&d->ip), d->port,
+				(d->ip.af > 0) ? ip_addr2a(&d->ip) : "0.0.0.0", d->port,
 				(d->server_name.s) ? d->server_name.s : "<default>");
 	}
 #endif