avcodec/decode: always free private_ref

There is no reason to keep this intact when decoding failed, specially
as private_ref is supposed to always be NULL when a frame is returned to
the user.

libavcodec/decode.c

@@ -613,7 +613,6 @@ static int decode_receive_frame_internal(AVCodecContext *avctx, AVFrame *frame)
     if (ret == AVERROR_EOF)
         avci->draining_done = 1;
 
-    /* free the per-frame decode data */
     if (!ret) {
         /* the only case where decode data is not set should be decoders
          * that do not call ff_get_buffer() */
@@ -631,10 +630,11 @@ static int decode_receive_frame_internal(AVCodecContext *avctx, AVFrame *frame)
                 }
             }
         }
-
-        av_buffer_unref(&frame->private_ref);
     }
 
+    /* free the per-frame decode data */
+    av_buffer_unref(&frame->private_ref);
+
     return ret;
 }