Different connecters simplified

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

src/tcp_connecter.hpp

@@ -74,7 +74,7 @@ namespace zmq
         int open ();
 
         //  Close the connecting socket.
-        int close ();
+        void close ();
 
         //  Get the file descriptor of newly created connection. Returns
         //  retired_fd if the connection was unsuccessfull.