h264: increase ref_poc size to 32 as it can be per field.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 8c851ef5a8)

libavcodec/mpegvideo.h

@@ -123,7 +123,7 @@ typedef struct Picture{
     int pic_id;                 /**< h264 pic_num (short -> no wrap version of pic_num,
                                      pic_num & max_pic_num; long -> long_pic_num) */
     int long_ref;               ///< 1->long term reference 0->short term reference
-    int ref_poc[2][2][16];      ///< h264 POCs of the frames used as reference (FIXME need per slice)
+    int ref_poc[2][2][32];      ///< h264 POCs of the frames/fields used as reference (FIXME need per slice)
     int ref_count[2][2];        ///< number of entries in ref_poc              (FIXME need per slice)
     int mbaff;                  ///< h264 1 -> MBAFF frame 0-> not MBAFF
     int field_picture;          ///< whether or not the picture was encoded in seperate fields