remove dead store in res_msend

The variable nss is set to zero in following line.
diff --git a/src/network/res_msend.c b/src/network/res_msend.c
index a47d18d..de7f615 100644
--- a/src/network/res_msend.c
+++ b/src/network/res_msend.c
@@ -52,7 +52,6 @@
 	timeout = 1000*conf->timeout;
 	attempts = conf->attempts;
 
-	nns = conf->nns;
 	for (nns=0; nns<conf->nns; nns++) {
 		const struct address *iplit = &conf->ns[nns];
 		if (iplit->family == AF_INET) {