timezone: sync to TZDB 2024b

timezone: sync to TZDB 2024b

Sync tzselect, zdump, zic to TZDB 2024b. This patch incorporates the
following TZDB source code changes:

6903dde3 Release 2024b
812aff32 Improve historical transitions in Mexico 1921-1997
52662566 Adjust to mailing list software change
7748036b Mention Internet RFC 9557
339e81d1 Mention Levine’s proposal to replace leap seconds
b4e6ad2d No leap second on 2024-12-31
7eb5bf88 Asia/Choibalsan is now an alias for Asia/Ulaanbaatar
43450cbf Improve historical data for Portugal and former possessions.
13d7348b Typo and validation fixes.
3c39cde8 Fix typo for “removed” in a comment
03fd9e45 More documentation updates for POSIX.1-2024
eb3bcceb POSIX.1-2014 is now published
913b0410 tzselect: support POSIX.1-2024 offset range
b5318b55 Document POSIX.1-2024 better
837609b7 Fix typo when making .txt man pages
d56ae6ee SUPPORT_C89 now defaults to 1, not 0
b1fe113d Port ! to Solaris make
8f1fd321 Avoid crash in Solaris 10 /usr/xpg4/bin/make
e0fcfdd6 Use ‘export VAR=VAL’ syntax
eba43166 Avoid an awk invocation via $'...'
36479a80 Avoid some subshells in tzselect
7f6cf054 * tzselect.ksh: Assume POSIX.2 awk.
a1cf1daf * tzselect.ksh: Assume POSIX.2 $PWD.
a9b8e536 Assume POSIX.2 command substitution
eaa4ef16 Avoid subshells when possible
9dac9eb7 Prefer $PWD to $(pwd) in Makefile
fada6a4c Prefer $(CMD) to `CMD` in Makefile
3e871b9a Assume POSIX.2 and eschew ‘expr’
c5d67805 difftime isn’t pure either
5857c056 * CONTRIBUTING: Document build assumptions.
6822cc82 ‘make check’ no longer depends on curl+Internet
cc6eb255 Document GCC bug 114833 and workaround
bcbc86bf Scale back on function attribute use
c0789e46 C23 [[reproducible]] and [[unsequenced]] fixups
bbd88154 More updates to GCC_DEBUG_FLAGS for GCC 14
1a35b7c8 Spelling fixes
f71085f2 POSIX.1-2024 removes asctime_r, ctime_r
70856f8e Adjust to refactored location of ctime, ctime_r
aacd151d Update GCC_DEBUG_FLAGS for GCC 14
967dcf3b Sub-second history for Maputo and Zurich
782d0826 Make EET, MET and WET links
a0b09c02 Mark CET, CST6CDT etc. as obsolescent
db7fb40d Document SMPTE timecodes and rolling leaps
97232e18 Don’t be so sure about leap seconds going away
5b6a74fb Update some URLs
a75a6251 * zic.8: Tweak for consistency.
1e75b31f Document what %s means before any rule applies
00c96cbb Conform to RFC 8536 section 3.2 for default type
3e944959 Document problems with stripped-down TZif readers
20fc91cf Shanks is likely wrong about Maputo switch to CAT
d99589b6 * zic.8: Add missing tab character.
94e6b3b0 Switch to %z in main dataform
2cd57b93 Treat W-Eur like Port when reguarding
ad6f6d94 Check that main.zi agrees with sources
a43b030f .gitignore: Add .pdf, .ps, .s. Remove obsolete ‘yearistype’.
253ca020 * theory.html: ‘CLT’ → ‘LTC’ (per Michael H Deckers)
a3dee8c8 * NEWS: ‘how’ → ‘now’ (thanks to Paul Goyette).
ea6341c5 * theory.html: Mention NASA and CLT (per Arthur David Olson).
0dcebe37 America/Scoresbysund matches America/Nuuk from now on
b1e07fb0 Update Vzic link (thanks to Allen Winter)
a4b05030 Fix wday/mday typo in previous patch
732a4803 Document how to detect mktime failure reliably
a64067e9 ziguard.awk: generalize for proposed Portugal patch
59c861fd Line up zdump examples
66c106c9 tzfile.5: srcfix
e5553001 Fix .RS/.RE problem in tzfile.5
d647eb01 Add Doctorow book
59d4a1ba Asia/Almaty matches Asia/Tashkent from now on
d4d3c3ba * asia: Update Philippine URLs (thanks to Guy Harris).
9fc11a27 Port unlikely overflow check to C23
b52a2969 Fix 2023d NEWS typo
e48c5b53 Cite "The NTP Leap Second File"
b1dc2122 Update Israel tz-link
6cf4e912 Extrapolate less from the 2022 CGPM resolution.

It fixes glibc build with gcc master [1].

Checked on x86_64-linux-gnu and on i686-linux-gnu.

[1] https://sourceware.org/pipermail/libc-alpha/2024-September/159571.html
Reviewed-by: Paul Eggert <eggert@cs.ucla.edu>