* Since the last change, the user launch_daemon would talk to the
registrar again.
* However, this also caused BRoster::Launch() to preregister the app,
which messed up our preallocated port.
* BRoster::Private::Launch() now allows to get the port that the
registrar created in such a case, and the launch_daemon will now just
use that one as default port.
* This lets us talk to the Deskbar again, and should fix#12455, as
well as #12454 (again).
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