From http://www.jwz.org/xscreensaver/xscreensaver-5.40.tar.gz
[xscreensaver] / utils / thread_util.h
2016-10-24 Zygo BlaxellFrom jwz.org/xscreensaver/xscreensaver-5.35.tar.gz
2014-11-16 Zygo BlaxellFrom jwz.org/xscreensaver/xscreensaver-5.31.tar.gz
2014-05-30 Zygo BlaxellFrom jwz.org/xscreensaver/xscreensaver-5.27.tar.gz