vcodec/error_resilience: use av_malloc_array()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/faxcompr: use av_malloc_array()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/ffv1: use av_malloc_array()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>