Fixed compiling error for ffmpeg with libavcodec less than 53.4.0
Fixed compiling error for ffmpeg with libavcodec less than 53.4.0

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