libndb: add AUTOLIB(resolv)

LGTM=rsc
R=rsc
https://codereview.appspot.com/97370043
diff --git a/src/libndb/sysdnsquery.c b/src/libndb/sysdnsquery.c
index b9661be..f7587ad 100644
--- a/src/libndb/sysdnsquery.c
+++ b/src/libndb/sysdnsquery.c
@@ -9,6 +9,8 @@
 #include <ndb.h>
 #include "ndbhf.h"
 
+AUTOLIB(resolv)
+
 static void nstrcpy(char*, char*, int);
 static void mkptrname(char*, char*, int);
 static Ndbtuple *doquery(char*, char*);