* Improve historical data for Mexico, Mongolia, and Portugal.
* System V names are now obsolescent.
* The main data form now uses %z.
* The code now conforms to RFC 8536 for early timestamps.
* Support POSIX.1-2024, which removes asctime_r and ctime_r.
* Assume POSIX.2-1992 or later for shell scripts.
* SUPPORT_C89 now defaults to 1.
OBS-URL: https://build.opensuse.org/package/show/Base:System/timezone?expand=0&rev=316
