mov: log and return early on non-positive stsd entry counts

Based on an FFmpeg patch by Michael Niedermayer <michael@niedermayer.cc>

libavformat/mov.c

@@ -1875,6 +1875,11 @@ static int mov_read_stsd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     avio_rb24(pb); /* flags */
     entries = avio_rb32(pb);
 
+    if (entries <= 0) {
+        av_log(c->fc, AV_LOG_ERROR, "invalid STSD entries %d\n", entries);
+        return AVERROR_INVALIDDATA;
+    }
+
     if (sc->extradata) {
         av_log(c->fc, AV_LOG_ERROR,
                "Duplicate stsd found in this track.\n");