Revert "mpeg12: move closed_gop from MpegEncContext to Mpeg1Context"

This reverts commit 3fc0830432.
The revert is done because the reasoning behind the commit was
flawed, closed_gop is not mpeg1/2 specific.

Conflicts:

	libavcodec/mpeg12.c
	libavcodec/mpeg12.h

libavcodec/mpeg12.c

@@ -2158,7 +2158,7 @@ static void mpeg_decode_gop(AVCodecContext *avctx,
     time_code_seconds  = get_bits(&s->gb, 6);
     time_code_pictures = get_bits(&s->gb, 6);
 
-    s1->closed_gop = get_bits1(&s->gb);
+    s->closed_gop = get_bits1(&s->gb);
     /*broken_link indicate that after editing the
       reference frames of the first B-Frames after GOP I-Frame
       are missing (open gop)*/
@@ -2438,7 +2438,7 @@ static int decode_chunks(AVCodecContext *avctx,
                 if (s2->last_picture_ptr == NULL) {
                 /* Skip B-frames if we do not have reference frames and gop is not closed */
                     if (s2->pict_type == AV_PICTURE_TYPE_B) {
-                        if (!s->closed_gop)
+                        if (!s2->closed_gop)
                             break;
                     }
                 }
@@ -2523,7 +2523,6 @@ static void flush(AVCodecContext *avctx)
     Mpeg1Context *s = avctx->priv_data;
 
     s->sync=0;
-    s->closed_gop = 0;
 
     ff_mpeg_flush(avctx);
 }

libavcodec/mpeg12.h

@@ -42,7 +42,6 @@ typedef struct Mpeg1Context {
     AVRational frame_rate_ext;       ///< MPEG-2 specific framerate modificator
     int sync;                        ///< Did we reach a sync point like a GOP/SEQ/KEYFrame?
     int full_pel[2];
-    int closed_gop;                  ///< GOP is closed
     int tmpgexs;
 } Mpeg1Context;
 

libavcodec/mpegvideo.c

@@ -2425,6 +2425,7 @@ void ff_mpeg_flush(AVCodecContext *avctx){
     s->current_picture_ptr = s->last_picture_ptr = s->next_picture_ptr = NULL;
 
     s->mb_x= s->mb_y= 0;
+    s->closed_gop= 0;
 
     s->parse_context.state= -1;
     s->parse_context.frame_start_found= 0;

libavcodec/mpegvideo.h

@@ -331,6 +331,7 @@ typedef struct MpegEncContext {
     int *lambda_table;
     int adaptive_quant;         ///< use adaptive quantization
     int dquant;                 ///< qscale difference to prev qscale
+    int closed_gop;             ///< MPEG1/2 GOP is closed
     int pict_type;              ///< AV_PICTURE_TYPE_I, AV_PICTURE_TYPE_P, AV_PICTURE_TYPE_B, ...
     int last_pict_type; //FIXME removes
     int last_non_b_pict_type;   ///< used for mpeg4 gmc b-frames & ratecontrol