vo_still_displaying() is racey with vo_request_wakeup_on_done() and above
that it doesn't work as expected. VO can run out of work and go to sleep
for 1000s, while the play thread still returns on vo_still_displaying()
check, because of a check `now < frame_end` so it never advances and go
to sleep itself.
This fixes dead lock that we have when image parameters changes during
playback.
This reverts commit 0c9ac5835b.
Fixes: #12575
44c398c3e1