avcodec/dvbsubdec: merge declaration and init

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/dvbsubdec: use av_freep() to avoid leaving stale pointers

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/crystalhd: use av_freep() to avoid stale pointers

this leaves some av_free() where the pointer is overwritten
shortly later

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/cngdec: Use av_freep() to avoid leaving stale pointers in memory

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/h264_parser: Use av_freep() to avoid leaving stale pointers

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