Fix ffmpeg wrapper compatibility with libavcodec > 53.25.0
Fix ffmpeg wrapper compatibility with libavcodec > 53.25.0

Based on pull request #685

apavlenko/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,apavlenko/opencv,apavlenko/opencv,apavlenko/opencv,opencv/opencv,opencv/opencv,apavlenko/opencv,apavlenko/opencv,opencv/opencv,opencv/opencv