avformat/utils: avoid overflow in compute_chapters_end() with huge durations

Fixes: usan_granule_overflow
Found-by: Thomas Guilbert <tguilbert@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/utils.c

@@ -3041,7 +3041,7 @@ static void compute_chapters_end(AVFormatContext *s)
     unsigned int i, j;
     int64_t max_time = 0;
 
-    if (s->duration > 0)
+    if (s->duration > 0 && s->start_time < INT64_MAX - s->duration)
         max_time = s->duration +
                        ((s->start_time == AV_NOPTS_VALUE) ? 0 : s->start_time);