message: videoio: av_frame_unref compilation fix
diff: @@ -1469,9 +1469,12 @@ bool CvCapture_FFMPEG::retrieveFrame(int, unsigned char** data, int* step, int*
  *height = frame.height;
  *cn = frame.cn;
  - if (sw_picture != picture) {
  +#if USE_AV_HW_CODECS
  + if (sw_picture != picture)
  + {
  av_frame_unref(sw_picture);
  }
  +#endif
  return true;
  }
  