mov: Don't allocate arrays with av_malloc that will be realloced

CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/mov.c

@@ -2373,7 +2373,7 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     if (!sc->ctts_count && sc->sample_count)
     {
         /* Complement ctts table if moov atom doesn't have ctts atom. */
-        ctts_data = av_malloc(sizeof(*sc->ctts_data));
+        ctts_data = av_realloc(NULL, sizeof(*sc->ctts_data));
         if (!ctts_data)
             return AVERROR(ENOMEM);
         sc->ctts_data = ctts_data;