avformat/cinedec: ask for sample when biBitCount isnt supported

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
examples/avio_reading: fix null dereference on error

Fixed CID1197052
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/oggparsevorbis: remove non functional null check

Fixes CID1197055

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