* hw/kdrive/ephyr/ephyrhostvideo.c/h:
(ephyrHostXVStopVideo): add this entry point.
* hw/kdrive/ephyr/ephyrvideo.c:
Basically add ReputImage and StopVideo implementations.
Now, when other windows obscur the video window, the reclipping
seems to be well handled using StopVideo and ReputImage.
To do this, I was obliged to save the frame in PutImage, so
that I could resend it un ReputImage.