Right now, if the same tracked sample is released at the same time
from two different threads it might happen that neither of them calls
the callback, because they might go through the critical section at
the same time (while neither has decremented the reference count yet).
Signed-off-by: Giovanni Mascellani <gmascellani@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>