Break out of select() on publish()/subscribe() etc.

Break out of select() on publish()/subscribe() etc.

When a call to publish()/subscribe()/unsubscribe()/disconnect() is made
and the client is using the threaded mode, the outgoing command will be
delayed by 0.5 seconds on average. This commit breaks out of select() to
remove the delay.

Change-Id: I7a669604c767abb0bcc399bdf1fe3b82c7ef9539