h261, h263 decoders: convert to RL_VLC.

Some additional optimizations in following patch.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
h261dec: Optimize new RL_VLC based decoding.

Together with the switch to RL_VLC this results in about
10% speedup for this inner loop.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
ituh263dec: Optimize new RL_VLC based decoding.

Together with the switch to RL_VLC this results in
a speedup of about 30% in this inner loop.
Overall speedup only relevant for medium to high bitrate
streams.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
ffserver: tests, use image2 instead of pgmyuv

Signed-off-by: Reynaldo H. Verdejo Pinochet <reynaldo@osg.samsung.com>