add last_updated field

include/llarp/router_contact.h

@@ -14,6 +14,7 @@ struct llarp_rc {
   llarp_pubkey_t pubkey;
   struct llarp_xi_list *exits;
   llarp_sig_t signature;
+  uint64_t last_updated;
 };
 
 bool llarp_rc_bdecode(struct llarp_alloc * mem, struct llarp_rc *rc, llarp_buffer_t *buf);