[tz] Need input - minimal tzdata install

[Paul Eggert]

On 7/19/21 2:42 PM, Patsy Griffin via tz wrote:
> We are looking at ways to reduce the amount of timezone data needed.
> Specifically, we are considering providing a minimal/UTC-only tzdata
> package.

The definition of "minimal" depends on what software you're using. For 
tzcode, the minimal/UTC-only tzdata should be trivial: it's the empty 
set. In other words, install no data files whatsoever. This is because 
tzcode defaults to UTC if nothing is installed. I think glibc behaves 
the same way. If you have some POSIX-compatible library that doesn't 
default to UTC in this way, you can set TZ='UTC0' in the environment.

Perhaps there's some software on your system that doesn't behave the 
same way that tzcode and glibc do, and that doesn't conform to POSIX. If 
so, you could use the following line:

Zone        Etc/UTC         0       -       UTC

as input to zic (or whatever other .zi parser your software is using), 
and then use TZ='Etc/UTC'.

We could add some documentation along those lines, or a Makefile rule to 
generate that one-line file, or something like that; the details would 
depend on what you need.