avcodec/smc: Mark decoder as init-threadsafe

Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/smc.c

@@ -484,4 +484,5 @@ AVCodec ff_smc_decoder = {
     .close          = smc_decode_end,
     .decode         = smc_decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };