Premature deallocation bug in XSUB fixed (issue 244)

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

src/xsub.cpp

@@ -211,7 +211,6 @@ void zmq::xsub_t::send_subscription (unsigned char *data_, size_t size_,
     //  Send it to the pipe.
     bool sent = pipe->write (&msg);
     zmq_assert (sent);
-    msg.close ();
 }