avcodec/cinepak: Mark decoder as init-threadsafe

Reviewed-by: Tomas Härdin <tjoppen@acc.umu.se>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/cinepak.c

@@ -522,4 +522,5 @@ AVCodec ff_cinepak_decoder = {
     .close          = cinepak_decode_end,
     .decode         = cinepak_decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };