VLCThumbnailer: don't render SPU

Sources/VLCMediaThumbnailer.m

@@ -205,6 +205,7 @@ static void display(void *opaque, void *picture)
     _mp = libvlc_media_player_new(self.libVLCinstance);
 
     libvlc_media_add_option([_media libVLCMediaDescriptor], "no-audio");
+    libvlc_media_add_option([_media libVLCMediaDescriptor], "no-spu");
     libvlc_media_add_option([_media libVLCMediaDescriptor], "avcodec-threads=1");
     libvlc_media_add_option([_media libVLCMediaDescriptor], "avcodec-skip-idct=4");
     libvlc_media_add_option([_media libVLCMediaDescriptor], "avcodec-skiploopfilter=3");