avcodec/rawdec: Support CODEC_CAP_PARAM_CHANGE

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/swfdec: Use side data to communicate w/h changes to the decoder

Fixes reading from freed data
Fixes part of Ticket3539

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>