misc/zoneinfo: Update to 2024b

Changes:

• 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.