h264: Print user data SEI under normal debug verbosity

Drop the need of setting -debug bugs since it's not a bug, and the
message is already under a AV_LOG_DEBUG log level. Instead only print
it when there is an actual string in it.

libavcodec/h264_sei.c

@@ -229,7 +229,7 @@ static int decode_unregistered_user_data(H264Context *h, int size)
     if (e == 1 && build > 0)
         h->x264_build = build;
 
-    if (h->avctx->debug & FF_DEBUG_BUGS)
+    if (strlen(user_data + 16) > 0)
         av_log(h->avctx, AV_LOG_DEBUG, "user data:\"%s\"\n", user_data + 16);
 
     for (; i < size; i++)