lavf: move a variable declaration to the block where it's used

libavformat/utils.c

@@ -1749,12 +1749,12 @@ static void fill_all_stream_timings(AVFormatContext *ic)
 static void estimate_timings_from_bit_rate(AVFormatContext *ic)
 {
     int64_t filesize, duration;
-    int bit_rate, i;
+    int i;
     AVStream *st;
 
     /* if bit_rate is already set, we believe it */
     if (ic->bit_rate <= 0) {
-        bit_rate = 0;
+        int bit_rate = 0;
         for(i=0;i<ic->nb_streams;i++) {
             st = ic->streams[i];
             if (st->codec->bit_rate > 0)