cbs: Add support functions for handling unit content references
Use the unit type table to determine what we need to do to clone the
internals of the unit content when making copies for refcounting or
writeability. (This will still fail for units with complex content
if they do not have a defined clone function.)
Setup and naming from a patch by Andreas Rheinhardt
<andreas.rheinhardt@gmail.com>, but with the implementation changed
to use the unit type information if possible rather than requiring a
codec-specific function.
projects / ffmpeg / commit