JDK-8218975 introduced a workaround for a bug in macOSX pthread support. At the time, it looked like that bug was fixed in OSX 10.14 (Mojave), which was the latest release at the time. (But we were still using and supporting earlier versions.)

The task here is to determine when the workaround is no longer needed (e.g. we no longer support sufficiently old versions), and remove the workaround when that's possible.