When the thread that got woken up by release() is supposed to release()
to wake up another thread, we were deadlocking. This happened because we
cleared the bit indicating that there was contention when the first
release(). Instead of storing a single bit, we now store the number of
threads waiting.
Task-number: QTBUG-66875
Change-Id: I72f5230ad59948f784eafffd15193873502ecba4
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
081c001deb