fix leak when open fails

Reference: /n/sources/patch/applied/dnsleak
Date: Fri Dec 15 21:05:24 CET 2006
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/ndb/dnresolve.c	Fri Dec 15 21:02:46 2006
+++ /sys/src/cmd/ndb/dnresolve.c	Fri Dec 15 21:02:36 2006
@@ -755,8 +755,9 @@
 
 	fd = udpport();
 	if(fd < 0)
-		return 0;
-	rv = netquery1(fd, dp, type, nsrp, reqp, depth, ibuf, obuf);
+		rv = 0;
+	else
+		rv = netquery1(fd, dp, type, nsrp, reqp, depth, ibuf, obuf);
 	close(fd);
 	free(ibuf);
 	free(obuf);