[tz] strftime %s

[Guy Harris]

On Jan 13, 2024, at 5:46 PM, Robert Elz via tz <tz at iana.org> wrote:

>  | much simpler than other approaches mentioned in this thread that would 
>  | add members to struct tm and therefore would be a major pain,
> 
> In practice, it is impossible.   struct tm exists in binary form
> in thousands of places that can't be updated.   If it weren't for
> the fact that tm_gmtoff and tm_zone already exist in essentially every
> implementation, and have done for years, there's no way they could
> have been added to the standard (and is why it took so long).

So we're presumably ruling out AIX and Solaris, for example, as implementations to count in the set of "essentially every implementation".