obs-ffmpeg: Workaround for a64 encoder bug

the Commodore A64 codecs seem to deref the video frame
too many times causing a crash.  For now just skip if this
codec.

plugins/obs-ffmpeg/obs-ffmpeg-output.c

@@ -361,6 +361,13 @@ static void close_video(struct ffmpeg_data *data)
 {
 	avcodec_close(data->video->codec);
 	avpicture_free(&data->dst_picture);
+
+	// This format for some reason derefs video frame
+	// too many times
+	if (data->vcodec->id == AV_CODEC_ID_A64_MULTI ||
+	    data->vcodec->id == AV_CODEC_ID_A64_MULTI5)
+		return;
+
 	av_frame_free(&data->vframe);
 }