avcodec/utils: Don't forget cleaning up when allocating priv_data fails

Allocating an AVCodecContext's priv_data used to be the first object
allocated in avcodec_open2(), so it was unnecessary to goto free_and_end
(which does the cleanup) upon error here. But this is no longer so since
f3a29b750a.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/utils.c

@@ -608,7 +608,7 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *code
             avctx->priv_data = av_mallocz(codec->priv_data_size);
             if (!avctx->priv_data) {
                 ret = AVERROR(ENOMEM);
-                goto end;
+                goto free_and_end;
             }
             if (codec->priv_class) {
                 *(const AVClass **)avctx->priv_data = codec->priv_class;