VC1 test container always uses time-base 1 ms, so we must convert
from whatever time-base the application gave us to that, otherwise
the video will play at ridiculous speeds.
It would be possible to signal that a container supports only one
time-base and have code in a layer above do the conversion, but
for a single format this seems over-engineered.
This also lists the objects from those two libraries as internal (by adding
the ff_ prefix) so that they can then be hidden via linker scripts.
(cherry picked from commit c6610a216e)
