avcodec/ffwavesynth: Check ts_end - ts_start for overflow

Fixes: signed integer overflow: 2314885530818453536 - -8926099139098304480 cannot be represented in type 'long'
Fixes: 15259/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FFWAVESYNTH_fuzzer-5764366093254656

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

libavcodec/ffwavesynth.c

@@ -267,7 +267,10 @@ static int wavesynth_parse_extradata(AVCodecContext *avc)
         in->type     = AV_RL32(edata + 16);
         in->channels = AV_RL32(edata + 20);
         edata += 24;
-        if (in->ts_start < cur_ts || in->ts_end <= in->ts_start)
+        if (in->ts_start < cur_ts ||
+            in->ts_end <= in->ts_start ||
+            (uint64_t)in->ts_end - in->ts_start > INT64_MAX
+        )
             return AVERROR(EINVAL);
         cur_ts = in->ts_start;
         dt = in->ts_end - in->ts_start;