avformat/voc_packet: Add a basic check on max_size

Fixes: signed integer overflow: -2147483648 - 4 cannot be represented in type 'int'
Fixes: 28127/clusterfuzz-testcase-minimized-ffmpeg_dem_VOC_fuzzer-4880586455646208

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

libavformat/voc_packet.c

@@ -44,6 +44,8 @@ ff_voc_get_packet(AVFormatContext *s, AVPacket *pkt, AVStream *st, int max_size)
                        AVINDEX_KEYFRAME);
 
     while (!voc->remaining_size) {
+        if (max_size < 4)
+            max_size = 0;
         type = avio_r8(pb);
         if (type == VOC_TYPE_EOF)
             return AVERROR_EOF;