Add -j/--jul to lttng UI and ABI

The JUL domain is set as unsupported in the session daemon so only the
client side is implemented with help updated.

Again, on the session daemon side, this is set as unsupported.

Signed-off-by: David Goulet <dgoulet@efficios.com>
Add jul.c/.h to sessiond code

This adds data structures to handle the JUL domain. The domain is added
to a ust session and created/destroyed in the trace-ust.c API.

Nothing is working yet, just putting the piece together.

Signed-off-by: David Goulet <dgoulet@efficios.com>
Add JUL registration thread

Listening on port 5345 by default and adds the --jul-tcp-port option to
the session daemon command line options.

At this commit, the thread is started and listening for incoming
registration but they are not handled.

This commit adds a new thread to the session daemon that is spawned by
default once the launched.

Signed-off-by: David Goulet <dgoulet@efficios.com>
Add jul-app ABI/API and handle registration

Registration is done in the jul thread and the created jul-app are
attached to existing UST app.

At this stage, there is no need for the UST app to be linked to the JUL
app but in the future, by adding new features, this will be needed.

Enable/Disable one or all events are supported. Also, once a JUL
application registers, it's updated with the already enabled events.

Signed-off-by: David Goulet <dgoulet@efficios.com>
Add lttng list -j command to list possible events

For the JUL domain, add the -j/--jul support for lttng list.

Signed-off-by: David Goulet <dgoulet@efficios.com>