[tz] Provide .tar.gz tarballs for tzdb

[Steve Summit]

I apologize for what is certainly an off-topic rant, but:

> > Why not use gzip for all?
>
> gzip doesn't compress as well as lzip.

But gzip compresses well enough, and storage is almost infinitely
cheap.

> Also, the benefits of switching to a better compression algorithm need 
> to be weighed against the maintenance hassle of adapting to the switch.

Absolutely.  And that hassle is HUGE.  Every few years, I have
to replace my monitor, after putting my fist through it out of
frustrated rage, because I've just downloaded some package I'm
interested in, but first I have to go through the yak-shaving
exercise of downloading and building a decompressor for the nifty
new "better" decompression algorithm it uses.  (I'm kidding about
the broken monitor part, but just barely.)

But, clearly, I'm just a cranky old Luddite.  Progress marches
on.  Please, let's not clutter this list with a bunch of zealous
endorsements of how Very Much Better the latest compression
algorithms are, and how stubborn I am for failing to appreciate
them.