the main process must chdir to /, since it cannot have daemon() do the
job at startup. After much anguish I accept dlg's solution of chdir
for the problem ("starting ntpd on a filesystem I want to unmount"),
but we cannot change the main-process daemon() call. Why? Because
the ntpd privsep design predates more modern designs where the config
file is parsed once, and configuration marshalled to the fork+exec
children. Instead each ntpd process re-parses the config, and if
we chdir before fork+exec startup, it will move the basedir causing
-f "relativepath" to fail.
discussed with florian