avcodec/012v: Mark decoder as init-threadsafe

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

libavcodec/012v.c

@@ -152,4 +152,5 @@ const AVCodec ff_zero12v_decoder = {
     .init           = zero12v_decode_init,
     .decode         = zero12v_decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };