avcodec/libtheoraenc: Check for av_fast_realloc() failure

Fixes CID1257799
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/libtheoraenc.c

@@ -99,8 +99,11 @@ static int get_stats(AVCodecContext *avctx, int eos)
         return AVERROR_EXTERNAL;
     }
     if (!eos) {
-        h->stats = av_fast_realloc(h->stats, &h->stats_size,
+        void *tmp = av_fast_realloc(h->stats, &h->stats_size,
                                    h->stats_offset + bytes);
+        if (!tmp)
+            return AVERROR(ENOMEM);
+        h->stats = tmp;
         memcpy(h->stats + h->stats_offset, buf, bytes);
         h->stats_offset += bytes;
     } else {