avcodec/avpacket: simplify freeing pkt->data

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/avpacket: use av_freep(), do not leave stale pointers in memory

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/proresenc_kostya: use av_freep(), do not leave stale pointers in memory

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/escape124: use av_freep(), do not leave stale pointers in memory

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