This is needed to cleanup everything correctly. In one particular
occurence, the InputManager still had pending selectors in the queue
which prevented the object from being released.
This resulted in playback position never saved, which is fixed now
with this change.

Also this fixes occasional crashes in debug mode as the ref count of
the current input thread is now correct on exit.

fixes #19704

(cherry picked from commit 5d0d2b0d

)
Signed-off-by: David Fuhrmann <dfuhrmann@videolan.org>