hevc: Make sure to update the current frame transfer characteristic

Otherwise the first decoded frame will still be tagged with the
original transfer instead of the alternative one.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

libavcodec/hevcdec.c

@@ -2729,7 +2729,7 @@ static int set_side_data(HEVCContext *s)
     if (s->sei.alternative_transfer.present &&
         av_color_transfer_name(s->sei.alternative_transfer.preferred_transfer_characteristics) &&
         s->sei.alternative_transfer.preferred_transfer_characteristics != AVCOL_TRC_UNSPECIFIED) {
-        s->avctx->color_trc = s->sei.alternative_transfer.preferred_transfer_characteristics;
+        s->avctx->color_trc = out->color_trc = s->sei.alternative_transfer.preferred_transfer_characteristics;
     }
 
     return 0;