Fix bug when elbg->utility_inc[elbg->numCB-1] == 1

Originally committed as revision 17926 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/elbg.c

@@ -105,7 +105,7 @@ static int get_high_utility_cell(elbg_data *elbg)
 {
     int i=0;
     /* Using linear search, do binary if it ever turns to be speed critical */
-    int r = av_lfg_get(elbg->rand_state)%(elbg->utility_inc[elbg->numCB-1]-1) + 1;
+    int r = av_lfg_get(elbg->rand_state)%elbg->utility_inc[elbg->numCB-1] + 1;
     while (elbg->utility_inc[i] < r)
         i++;