[tz] disclaimer removals

[Christos Zoulas]

On Jun 25, 11:15pm, eggert at cs.ucla.edu (Paul Eggert) wrote:
-- Subject: Re: [tz] disclaimer removals

| Thanks, I pushed that into github.

Please fix it so that it does not pass char into the isfoo() functions
since they have undefined results for negative values other than -1.

http://pubs.opengroup.org/onlinepubs/009695399/functions/isalnum.html

An easy fix is to cast the value to unsigned char.

christos