We used to create all sessions that listen to displays during startup.
Therefore, all displays were kind of "hotplugged". However, we must also
send already existing displays to new sessions so we can create them
during runtime just fine.
This simply calls the session-callback during session-registration so you
must be fine getting the session callback when calling
kmscon_session_register().
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
c22fac0129