avcodec/libx264: Don't unnecessarily add in-band extradata

The check here is meant to check for whether avcintra-class option
(default value -1) has been set; yet it checks for the x264_param_t
value where 0 is the default value (treated as "no avcintra-mode"
by x264). This meant that in-band extradata has been added unnecessarily
when using global headers; furthermore, the first output packet
had two x264 SEIs.

Reviewed-by: Limin Wang <lance.lmwang@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/libx264.c

@@ -944,7 +944,7 @@ static av_cold int X264_init(AVCodecContext *avctx)
 
 #if X264_BUILD >= 142
     /* Separate headers not supported in AVC-Intra mode */
-    if (x4->params.i_avcintra_class >= 0)
+    if (x4->avcintra_class >= 0)
         x4->params.b_repeat_headers = 1;
 #endif