sem_close(2) on macOS

The text a83508f1c597, as Mac OS X 10.1.5, Mac OS X 10.1.4, Mac OS X 10.1.3, Mac OS X 10.1.2, Mac OS X 10.1.1, Mac OS X 10.1, Mac OS X 10.0.4, Mac OS X 10.0.1, Mac OS X 10.0 shipped it.

close a named semaphore

sem_close(2) on macOS now