vout: fix use-after-free, wait on correct date
vout: fix use-after-free, wait on correct date

The mwait() call dereferenced a potentially no longer referenced picture
(if the display was filtered).

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc