Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Bring our tzcode up to date.

* Replay 2010[acflm] which had been merged but not recorded.
* Merge 2010n.
* Reorganize (unsplit) the code to match the upstream layout.
* Merge 2022[cdefg].

MFC after: 1 week
Sponsored by: Klara, Inc.