NAME
       EXPUNGE - indicate a desire to remove the Audio device

   FUNCTION
       The Expunge routine is called when a user issues a remdevice call.  by
       the time it is called, the device has already been removed from the
       device list, so no new opens will succeed.  The existence of any other
       users of the device, as determined by the device open count being
       non-zero, will cause the Expunge to be deferred.  When the device is
       not in use, or no longer in use, the Expunge is actually performed.