check for invalid protocol when dispatch fails

treat ISC_R_INVALIDPROTO as a networking error when it occurs.

lib/dns/resolver.c

@@ -7791,6 +7791,7 @@ rctx_dispfail(respctx_t *rctx) {
 	case ISC_R_NETUNREACH:
 	case ISC_R_CONNREFUSED:
 	case ISC_R_CONNECTIONRESET:
+	case ISC_R_INVALIDPROTO:
 	case ISC_R_CANCELED:
 	case ISC_R_SHUTTINGDOWN:
 		rctx->broken_server = rctx->result;