Tested to compile with lavc major bump.
Signed-off-by: Mans Rullgard <mans@mansr.com>
(cherry picked from commit b2ed95ec48aceb21a9bb47af85d259ee52b8b7ea)
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 c6610a216ed2948885772154a2eed696e0cb4aca)