mpeg12: move Mpeg1Context from mpeg12.c to mpeg12.h

It will be used in vdpau code.

libavcodec/mpeg12.c

@@ -1106,19 +1106,6 @@ static int mpeg_decode_mb(MpegEncContext *s, DCTELEM block[12][64])
     return 0;
 }
 
-typedef struct Mpeg1Context {
-    MpegEncContext mpeg_enc_ctx;
-    int mpeg_enc_ctx_allocated; /* true if decoding context allocated */
-    int repeat_field; /* true if we must repeat the field */
-    AVPanScan pan_scan;              /**< some temporary storage for the panscan */
-    int slice_count;
-    int swap_uv;//indicate VCR2
-    int save_aspect_info;
-    int save_width, save_height, save_progressive_seq;
-    AVRational frame_rate_ext;       ///< MPEG-2 specific framerate modificator
-    int sync;                        ///< Did we reach a sync point like a GOP/SEQ/KEYFrame?
-} Mpeg1Context;
-
 static av_cold int mpeg_decode_init(AVCodecContext *avctx)
 {
     Mpeg1Context *s = avctx->priv_data;

libavcodec/mpeg12.h

@@ -30,6 +30,19 @@
 extern VLC ff_dc_lum_vlc;
 extern VLC ff_dc_chroma_vlc;
 
+typedef struct Mpeg1Context {
+    MpegEncContext mpeg_enc_ctx;
+    int mpeg_enc_ctx_allocated; /* true if decoding context allocated */
+    int repeat_field; /* true if we must repeat the field */
+    AVPanScan pan_scan;              /**< some temporary storage for the panscan */
+    int slice_count;
+    int swap_uv;//indicate VCR2
+    int save_aspect_info;
+    int save_width, save_height, save_progressive_seq;
+    AVRational frame_rate_ext;       ///< MPEG-2 specific framerate modificator
+    int sync;                        ///< Did we reach a sync point like a GOP/SEQ/KEYFrame?
+} Mpeg1Context;
+
 extern uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];
 
 void ff_mpeg12_common_init(MpegEncContext *s);