[tz] Undoing the effect of the new alike-since-1970 patch

[Paul Eggert]

On 9/14/21 2:59 PM, Paul Eggert wrote:

> Since zone.tab is present only for compatibility reasons, it makes sense 
> to revert the changes to it. Proposed patch attached.

Almaz, have you had a chance to look at that patch? It's archived here:

https://mm.icann.org/pipermail/tz/2021-September/030388.html

I ask because it looks like we'll need a new tzdb release soon, due to 
Samoa's recent decision to discontinue DST:

https://mm.icann.org/pipermail/tz/2021-September/030398.html

and I'm hoping that the patch would ameliorate at least some of the 
potential compatibility issues mentioned in the alike-since-1970 area.