cmdutils: remove ansi from the list of broken codecs.

It's not relying on get_buffer() initializing the frame since
99e36ddd3e.

cmdutils.c

@@ -1566,7 +1566,7 @@ static int alloc_buffer(FrameBuffer **pool, AVCodecContext *s, FrameBuffer **pbu
     /* XXX this shouldn't be needed, but some tests break without this line
      * those decoders are buggy and need to be fixed.
      * the following tests fail:
-     * ansi, aasc, fraps-v1, qtrle-1bit
+     * aasc, fraps-v1, qtrle-1bit
      */
     memset(buf->base[0], 128, ret);