[tz] Add option to act like global-tz

[Paul Eggert]

On 8/15/22 12:23, Robert Elz via tz wrote:

> What I need is for the data to be in the files it has always been in.

In what sense is that not true for the tarball format in question[1]? 
What programs go awry if that tarball's data are used, and what are the 
symptoms of these failures?

If the main problem is that a user who wants to hand-edit this data will 
not know to edit 'etcetera' rather than (say) 'australasia', then it'd 
be easy to change the tarball generator so that instead of 'australasia' 
being empty it would contain a comment like "# Please edit the file 
'etcetera' instead."; would that help?

If the problem is somewhere else it'd be helpful to know what it is.

[1] Here's the latest iteration of the tarball format in question:

https://www.cs.ucla.edu/~eggert/tz/tzdata2022b-5-gc9ba895-tailored.tar.gz