Remove timeouts from remote communication loop.

The select() now blocks until there's work to do instead of relying on a
small timeout value which can cause unproductive use of cpu cycles.

src/DNS_Mgr.cc

@@ -1217,9 +1217,10 @@ void DNS_Mgr::IssueAsyncRequests()
 		}
 	}
 
-void  DNS_Mgr::GetFds(int* read, int* write, int* except)
+void  DNS_Mgr::GetFds(std::vector<int>* read, std::vector<int>* write,
+                      std::vector<int>* except)
 	{
-	*read = nb_dns_fd(nb_dns);
+	read->push_back(nb_dns_fd(nb_dns));
 	}
 
 double DNS_Mgr::NextTimestamp(double* network_time)