avcodec/mpegvideo: remove AVFrame padding, as the hack isnt needed anymore

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

libavcodec/mpegvideo.h

@@ -93,7 +93,6 @@ struct MpegEncContext;
  */
 typedef struct Picture{
     struct AVFrame *f;
-    uint8_t avframe_padding[1024]; // hack to allow linking to a avutil with larger AVFrame
     ThreadFrame tf;
 
     AVBufferRef *qscale_table_buf;