Fix a crash that would happen when attempting to unload the app_queue module.

The problem was that when the refcount on the queue hit 0, the destructor was
called, and inside the destructor, another function was called which would increase
the refcount back to 1 again and then decrease it again back to 0 for every member
in the queue. This meant that the destructor was being recursively called, leading
to a double free of the queue. This is now fixed by making sure to unlink the
queue from the queues container prior to the final unref of the queue.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@111533 65c4cc65-6c06-0410-ace0-fbb531ad65f3