avformat/cafdec: Check that nb_frasmes fits within 64bit

Fixes: signed integer overflow: 1099511693312 * 538976288 cannot be represented in type 'long'
Fixes: 50993/clusterfuzz-testcase-minimized-ffmpeg_dem_CAF_fuzzer-6565048815845376

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

libavformat/cafdec.c

@@ -387,7 +387,7 @@ static int read_header(AVFormatContext *s)
 
 found_data:
     if (caf->bytes_per_packet > 0 && caf->frames_per_packet > 0) {
-        if (caf->data_size > 0)
+        if (caf->data_size > 0 && caf->data_size / caf->bytes_per_packet < INT64_MAX / caf->frames_per_packet)
             st->nb_frames = (caf->data_size / caf->bytes_per_packet) * caf->frames_per_packet;
     } else if (ffstream(st)->nb_index_entries && st->duration > 0) {
         if (st->codecpar->sample_rate && caf->data_size / st->duration > INT64_MAX / st->codecpar->sample_rate / 8) {