This allows detecting changes and regressions in side data related code, same as what
framecrc does for before already for packet data itself.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Always use the functionality of the latter, which makes more sense as it
avoids losing keyframes due to vsync code dropping frames.
Deprecate the 'source_no_drop' value, as it is now redundant.