ntpd: leap-seconds.list expiration

Noticed recently (in both my upgraded and newly-installed hosts) that the
leap-seconds.list file is in danger of expiration very soon (12/28). It
appears the default download location in /etc/defaults/rc.conf (
https://www.ietf.org/timezones/data/leap-seconds.list) no longer carries
this file, or at least it says plainly so when I try to fetch it.

I've been able to work around it locally by setting ntp_leapfile_sources="
https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list" in
/etc/rc.conf from IERS, though in searching where to fetch this there are
questions of copyright in regards to distribution so while this should work
for end-users I don't know how applicable this would be upstream (submitted
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=275737). I figured I'd
throw it out here for visibility to operators as my workaround should work
in that case.


-Michael Proto