toolchain: musl: Update to version 1.2.3

toolchain: musl: Update to version 1.2.3

Changes:
new features:
- qsort_r function (POSIX-future)
- pthread_getname_np extension function
- hard float on SPE FPU for powerpc-sf
- SEEK_DATA and SEEK_HOLE exposed in unistd.h (Linux extensions)

compatibility:
- free now preserves errno (POSIX-future requirement)
- setjmp is declared explicitly with returns_twice for non-GCC compilers
- macro version of isascii is no longer defined for C++
- dynamic linker now tolerates zero-length LOAD segments
- epoll_[p]wait is now a cancellation point
- pwd/grp functions no longer fail on systems without AF_UNIX support
- POSIX TZ parsing is stricter to allow more names to fallback to files
- NULL is now defined as nullptr when used in C++11 or later
- gettext now accepts null pointer as argument

bugs fixed:
- old regression in wcwidth of Hangul combining (vowel/final) letters
- duplocale used wrong malloc when malloc was replaced (1.2.2 regression)
- fmaf rounded wrong on archs without FE_TOWARDZERO (all softfloat archs)
- popen didn't honor requirement not to leak other popen pipe fds to child
- aligned_alloc and variants crashed on allocation failure
- dl_iterate_phdr reported incorrect module TLS pointers
- mishandling of some inputs in acoshf and expm1f and functions using them
- potentially wrong-sign zero in cproj functions at infinity
- multiple bugs in legacy function cuserid
- minor posix_spawn file actions API conformance issues
- pthread_setname_np fd leak
- out-of-bound read in zoneinfo handling with distant-past times
- out-of-tree builds lacked generated debug cfi for x86 asm

arch-specific bugs fixed:
- powerpc (32-bit) struct shmid_ds layout was wrong for some fields
- time64 struct layout was wrong in sound ioctl fallback (32-bit archs)

In addition it contains the following improvements:
* protect stack canary from leak via read-as-string by zeroing second byte
* fix excessively slow TLS performance on some mips models

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Acked-by: Rui Salvaterra <rsalvaterra@gmail.com>
Tested-by: Rui Salvaterra <rsalvaterra@gmail.com>
Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>