mxfdec: remove unused last_index_duration

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

libavformat/mxfdec.c

@@ -952,7 +952,6 @@ static int mxf_get_sorted_table_segments(MXFContext *mxf, int *nb_sorted_segment
     int i, j, nb_segments = 0;
     MXFIndexTableSegment **unsorted_segments;
     int last_body_sid = -1, last_index_sid = -1, last_index_start = -1;
-    uint64_t last_index_duration = 0;
 
     /* count number of segments, allocate arrays and copy unsorted segments */
     for (i = 0; i < mxf->metadata_sets_count; i++)
@@ -1003,7 +1002,6 @@ static int mxf_get_sorted_table_segments(MXFContext *mxf, int *nb_sorted_segment
         last_body_sid    = best_body_sid;
         last_index_sid   = best_index_sid;
         last_index_start = best_index_start;
-        last_index_duration = best_index_duration;
     }
 
     av_free(unsorted_segments);