mov: do not misreport empty stts

Return -1 instead of ENOMEM if entries is 0.
Fixes a av_malloc(0) crash in macosx.

libavformat/mov.c

@@ -1461,8 +1461,8 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     av_dlog(c->fc, "track[%i].stts.entries = %i\n",
             c->fc->nb_streams-1, entries);
 
-    if (entries >= UINT_MAX / sizeof(*sc->stts_data))
-        return -1;
+    if (!entries || entries >= UINT_MAX / sizeof(*sc->stts_data))
+        return AVERROR(EINVAL);
 
     sc->stts_data = av_malloc(entries * sizeof(*sc->stts_data));
     if (!sc->stts_data)