[tz] Add option to act like global-tz

[Stephen Colebourne]

On Mon, 15 Aug 2022 at 21:19, Robert Elz via tz <tz at iana.org> wrote:
> So, if you don't make a 2022btgz version available, I guess I will go back
> to manually inserting the updates, as I have done previously.

global-tz 2022bgtz is already available (and built into Joda-Time and
ThreeTen-Backport)
https://github.com/JodaOrg/global-tz/releases

(In the short term it was better to go through the pain and get a
version of tzdb I'm confident of rather than the PACKRATLIST
alternative. However, as I've said previously I don't particularly
want to maintain that in the medium or long term).

Paul, extrapolating from Robert's point is I think one I've made
before: that it is much simpler to start with the data in the correct
files and generate the merged form automatically for those that want
it merged than it is to start with the merged form and try to recreate
the data in the correct files.

Robert, if there is something specific about global-tz that is "wrong"
in your opinion, such as the contents of zonetab, feel free to raise
an issue and we can discuss it there to see if anything can/should be
done.

thanks
Stephen