Improved cropping of the bottom 8 lines of 1088-line video.

Refs #11358.  Reverts 9d9de7b75d5354c9130526311a0c74d7172ebe6d and
cleans up the bottom 8 lines by applying a crop filter to the source.
This is tested for the XVideo output method.

The VDPAU output method does not use the standard filter mechanism,
but it works fine on 1088-line video until the h.264 parser thinks the
resolution has changed from 1080 to 1088 lines.  To compensate, we
don't acknowledge a resolution change when this happens.