The application registration thread receives new connections from
applications, provides them to the dispatch thread. The dispatch
thread, in turn, forwards the command and notification sockets of
applications (liblttng-ust) to the application management and
application notification threads.
Not shutting down the application registration thread is problematic
since application connections will be accepted but not associated
to an "ust_app" structure as the following threads are no longer
present.
The remaining threads can then be safely torn down as part of the
orphaned threads.
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>