avformat/mov: Check sample_count and auxiliary_info_default_size to be 0

This combination causes 0 size arrays to be allocated and to leak later

Fixes: memleak
Fixes: 64342/clusterfuzz-testcase-minimized-ffmpeg_dem_MOV_fuzzer-4520993686945792

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

libavformat/mov.c

@@ -6994,6 +6994,9 @@ static int mov_read_saiz(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     sample_count = avio_rb32(pb);
 
     if (encryption_index->auxiliary_info_default_size == 0) {
+        if (sample_count == 0)
+            return AVERROR_INVALIDDATA;
+
         encryption_index->auxiliary_info_sizes = av_malloc(sample_count);
         if (!encryption_index->auxiliary_info_sizes)
             return AVERROR(ENOMEM);