* Mexico will no longer observe DST except near the US border.
* Chihuahua moves to year-round -06 on 2022-10-30.
* Fiji no longer observes DST.
* Move links to 'backward'.
* In vanguard form, GMT is now a Zone and Etc/GMT a link.
* zic now supports links to links, and vanguard form uses this.
* Simplify four Ontario zones.
* Fix a Y2438 bug when reading TZif data.
* Enable 64-bit time_t on 32-bit glibc platforms.
* Omit large-file support when no longer needed.
* In C code, use some C23 features if available.
* Remove no-longer-needed workaround for Qt bug 53071.