timezone: sync to tzdb 2026b

timezone: sync to tzdb 2026b

Sync tzselect, zdump, zic to tzdb 2026b.

This fixes some buffer and integer overflows in zic,
adds new zic options -D, -m and -u inspired by FreeBSD,
and raises zic’s maximum number of abbreviation bytes
per timezone from 50 to 256.

This patch incorporates the following tzdb source code changes:

f9d30685 Output a minimal time zone designation table
37a4d178 Fix zic overflow bug with too-large offsets
4392f2dc zic now checks for signals more often
99a08a66 Fix zic buffer overflow when computing TZ
d63b9287 zic: keep needed last transition to new type
d005045d Pacify clang -Wunterminated-string-initialization
e67b08d3 Port to C23 strchr macro
3d4b4e46 Add zic.c overflow commentary
d9101b88 zic now a bit safer for overflows near 2**63
b23fa8e0 zic now allows more than 50 leap seconds
4ff518d2 Increase TZ_MAX_CHARS from 50 to 256
75d3b73b New -DTZ_RUNTIME_LEAPS=0 build-time option
87343c6e TZ_MAX_TIMES must be at least 310 now
fc8f1b68 Simplify int_fast32_t definition on C89 platforms
24581465 Remove TZDEFRULES ("posixrules") from localtime.c
fc708427 zic now warns about -p
b09a3f23 Port TWOS_COMPLEMENT to signed-magnitude hosts
56b7a24a Make sure 2**31 - 1 is signed
9068ab78 zic no longer generates utoff == -2**31
cb6f9b3b Omit unnecessary L suffixes
c37fbc32 Clarify when ‘__attribute__((pure))’ is a hack
859690a7 Fix some unsequenced/reproducible commentary
9c772ca7 Port to POSIX.1-2001 fflush
10f93018 Omit no-op transitions when Rule+Zone cancel
a0b09b52 Fix unlikely backslash bug in scripts
2cbd3a71 Allow builder to override GRANDPARENTED
c7257626 not used at → used outside
faed4bd3 Clarify <sys/auxv.h> vs getauxval
df08e6a1 Port mode_t (and gid_t, uid_t) to MS-Windows
6127d375 New zic option -u, inspired by FreeBSD
813c9ee0 New zic option -m, inspired by FreeBSD
987ea89c New zic option -D, inspired by FreeBSD
cc377b07 Simplify mkdir situation
cd994a90 Simplify !HAVE_POSIX_DECLS situation
052ddf76 Minor gettext macro improvements
d9018f1c Refactor duplicate duplicate-option code
8d65db97 Prefer fdopen to umask in zic
d7edca6e Omit “'”s from zic usage message
a09ba7a5 getopt returns -1 (not EOF) on failure
e22d410c zic now uses is_digit
f57cadda Always invoke umask at start
242a8338 Fix mode_t issues on MS-Windows
2fecd606 MKDIR_UMASK → MKDIR_PERMS refactoring
90ef088a Move static_assert to top level
41576478 Port better to platforms lacking mempcpy
90a08d3e * private.h: Include stddef.h early enough
aa8b35fe Simplify port to NetBSD struct __state
cd2fddf7 Port to -DHAVE_SYS_STAT_H=0 -DHAVE_POSIX_DECLS=0
8470e759 Pacify GCC 15 -Wunterminated-string-initialization
8817d42f Prefer mempcpy to doing it by hand
87abb113 Tighten security checks on TZ values
c87f0918 Use strnlen
07f7f31a Fix preprocessor indenting
3adf4123 Add offtime_r à la FreeBSD and NetBSD
b807a31e Don’t depend on ‘true’ for tzselect
ddffc800 * zic.c: Fix misspelled comment (thanks to Jonathan Wakely).
7063d08c Fix bug with -d RELATIVE -t ABSOLUTE
e8920e76 Rename emalloc to xmalloc.
e8e1a3d2 NetBSD defines STD_INSPIRED functions
3411494c Define _CRT_DECLARE_NONSTDC_NAMES for MS-Windows
7c909166 Define NOMINMAX for MS-Windows
24a4d97f 'zdump -' now reads from stdin
e6d6bc3e Pacify gcc -Wsuggest-attribute=format sans snprintf in zdump
99557862 TZNAME_MAXIMUM defaults to 254, not 255
fe5be99d Be more consistent about macro true/false vs 1/0
31f483a1 Remove dependency of asctime on strftime
7ef7ed06 Simplify timeoff redefinition
1bd67a4b Move MKTIME_MIGHT_OVERFLOW definition
67f7e8ab Pacify GCC 15ish -Wzero-as-null-pointer-constant
535a4e8b Pacify GCC 15ish -Wleading-whitespace=blanks
0706ef0b Move iinntt definition
ea814e99 strftime %s no longer is limited to time_t range
41e5344e Fix bug near the year 2**31 - 1 - 1900
4e1de249 Pacify gcc -Wsuggest-attribute=const
ebd2ed92 Don’t define _FILE_OFFSET_BITS if _TIME_BITS
26a649a1 Improve zdump overflow checking
9c8221d7 * private.h: Fix timeoff comment.
9db906a0 Switch from RFC 8536 to 9636 for documentation
af54a9e8 Port better to glibc when used internally there

Checked on x86_64-linux-gnu.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>