correcter mpeg4 headers

Originally committed as revision 1376 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpegvideo.h

@@ -435,6 +435,7 @@ typedef struct MpegEncContext {
     INT8 (*field_select_table)[2];   /* wtf, no really another table for interlaced b frames */
     int t_frame;                     /* time distance of first I -> B, used for interlaced b frames */
     int padding_bug_score;           /* used to detect the VERY common padding bug in MPEG4 */
+    int last_vo_picture_number;      /* last picture number for which we added a VOS/VO/VOL header */
 
     /* divx specific, used to workaround (many) bugs in divx5 */
     int divx_version;