avformat/utils: wrap_timestamp() is only needed for less than 64 bits

Fixes: shift exponent 64 is too large for 64-bit type 'unsigned long long'
Fixes: 26497/clusterfuzz-testcase-minimized-ffmpeg_dem_AVI_fuzzer-5690188355076096
Fixes: 26903/clusterfuzz-testcase-minimized-ffmpeg_dem_LUODAT_fuzzer-5641466929741824

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/utils.c

@@ -101,7 +101,7 @@ static int is_relative(int64_t ts) {
  */
 static int64_t wrap_timestamp(const AVStream *st, int64_t timestamp)
 {
-    if (st->internal->pts_wrap_behavior != AV_PTS_WRAP_IGNORE &&
+    if (st->internal->pts_wrap_behavior != AV_PTS_WRAP_IGNORE && st->pts_wrap_bits < 64 &&
         st->internal->pts_wrap_reference != AV_NOPTS_VALUE && timestamp != AV_NOPTS_VALUE) {
         if (st->internal->pts_wrap_behavior == AV_PTS_WRAP_ADD_OFFSET &&
             timestamp < st->internal->pts_wrap_reference)