avcodec/ylc: thread safe initialization is possible with this codec

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/ylc.c

@@ -494,4 +494,5 @@ AVCodec ff_ylc_decoder = {
     .close          = decode_end,
     .decode         = decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };