Add listen-on-v6 {none;}; , since without it, v6 was binding v4 mapped

sockets and causing failures on some platforms

bin/tests/system/dnssec/ns2/named.conf

@@ -5,6 +5,7 @@ options {
 	port 5300;
 	pid-file "named.pid";
 	listen-on { 10.53.0.2; };
+	listen-on-v6 {none;};
 	recursion no;
 	notify yes;
 };