avcodec/exr: favor av_freep() over av_free() for saftey

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/exr: fix null pointer dereference

Fixes CID1108582

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
ffv1enc: use 64bit in maxsize calculation

This isnt needed but it cant hurt, its also more consistent with
how its calculated a few lines before.

See: CID1108593
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/h264_parser: fix order of operations

Fixes CID1108576

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