musl: update to 1.2.6

musl: update to 1.2.6

Update musl C library to 1.2.6. Fixes CVE-2025-26519

* Patches refreshed. Unnecessary upstream patch removed.

* Add a post-release patch for timezone handling in datetime string
  matching (affecting at least uhttpd):
  bug report: https://www.openwall.com/lists/musl/2026/03/22/3
  fix: https://www.openwall.com/lists/musl/2026/03/30/6

1.2.6 release notes
https://git.musl-libc.org/cgit/musl/tree/WHATSNEW?id=9fa28ece75d8a2191de7c5bb53bed224c5947417

new features:
- posix_getdents interface (new in POSIX-2024)
- renameat2 interface (linux extension)
- iconv support for CP858
- vdso clock_gettime for riscv{32,64}, powerpc{,64}, and s390x
- loongarch64 TLSDESC support
- exposed __getauxval for compiler runtime use detecting cpu features

compatibility:
- initgroups no longer artificially limits number of supplementary groups
- getusershell now skips blank lines and comments
- exit is now explicitly thread-safe (possible future requirement)
- atexit now fails rather than deadlocking if called from late dtor
- strerror now has error strings for EUCLEAN and ENAVAIL
- isatty no longer collapses errors to ENOTTY
- sched.h namespace pollution with _GNU_SOURCE is reduced
- hasmntopt now matches only whole options, not arbitrary substrings
- shadow.h no longer declares an unimplemented sgetspent interface
- vdso with missing sysv hash table (only gnu hash) is now supported

conformance:
- pwrite now handles O_APPEND correctly, reports error if it can't
- mbnrtowcs now conforms to new POSIX-2024 requirement for partial character
- iconv GBK now properly includes euro symbol
- strptime now accepts conversion specifiers added in POSIX-2024
- inet_ntop IPv6 "zero compression" now conforms to RFC 5952

bugs fixed:
- iconv euc-kr decoder could do oob writes on invalid inputs (CVE-2025-26519)
- iconv shift_jis decoder could produce wrong outputs for some invalid inputs
- printf did not honor hex float precision correctly in some cases
- lost or delayed wakes in sem_post under race condition
- termios input speed handling was wrong
- strcasestr failed to match zero-length needle
- fma handled corner case with negative zero wrongly
- syslog LOG_MAKEPRI macro was incorrect
- timer_create is no longer affected by known pthread_barrier bugs
- sysconf(_SC_MINSIGSTKSZ) computed min size incorrectly
- statx emulation left some fields uninitialized
- mntent wrongly included final newline in parsed field output
- SIGEV_THREAD timers could abort process if SIGTIMER became unblocked
- bind_textdomain_codeset returned wrong value

arch-specific bugs fixed:
- early dynamic linker handled page size wrong on dynamic pagesize archs
- arm and aarch64 crti/n files had wrong alignment
- m68k POLLWRNORM and POLLWRBAND values were incorrect
- x32 mq ABI was mismatched

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>
Link: https://github.com/openwrt/openwrt/pull/22547
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>