shorten: Extend fixed_coeffs to properly support pred_order 0

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
(cherry picked from commit b2148faca9e9e553c14b27844b56e367c85a777e)
Signed-off-by: Reinhard Tartler <siretart@tauware.de>
mov: Don't allocate arrays with av_malloc that will be realloced

CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit b698542ad83284fbb8c22404e3cafeb2dd739d38)
Signed-off-by: Reinhard Tartler <siretart@tauware.de>
avi: directly resync on DV in AVI read failure

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
(cherry picked from commit ceec6e792e4b5baaa23b220f4fd33417631f5288)
Signed-off-by: Reinhard Tartler <siretart@tauware.de>