clatd: move send_dad out of event_loop() into main()

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Id74ad4adf861182d928676213c77a24675c358a4
diff --git a/clatd/clatd.h b/clatd/clatd.h
index e170c58..5b2b2e6 100644
--- a/clatd/clatd.h
+++ b/clatd/clatd.h
@@ -54,6 +54,8 @@
 
 extern volatile sig_atomic_t running;
 
+void send_dad(int fd, const struct in6_addr* tgt);
+
 void event_loop(struct tun_data *tunnel);
 
 /* function: parse_int