avformat/utils: Fix integer overflow in end time calculation in update_stream_timings()

Fixes: crbug 829153
Reported-by: Matt Wolenetz <wolenetz@google.com>
Reviewed-by: Matt Wolenetz <wolenetz@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/utils.c

@@ -2648,7 +2648,7 @@ static void update_stream_timings(AVFormatContext *ic)
     else if (start_time > start_time_text)
         av_log(ic, AV_LOG_VERBOSE, "Ignoring outlier non primary stream starttime %f\n", start_time_text / (float)AV_TIME_BASE);
 
-    if (end_time == INT64_MIN || (end_time < end_time_text && end_time_text - end_time < AV_TIME_BASE)) {
+    if (end_time == INT64_MIN || (end_time < end_time_text && end_time_text - (uint64_t)end_time < AV_TIME_BASE)) {
         end_time = end_time_text;
     } else if (end_time < end_time_text) {
         av_log(ic, AV_LOG_VERBOSE, "Ignoring outlier non primary stream endtime %f\n", end_time_text / (float)AV_TIME_BASE);