Auto-sync with upstream branch master
    
    Upstream commit: 3ec5d83d2a237d39e7fd6ef7a0bc8ac4c171a4a5
    
    - Drop glibc-fedora-__libc_multiple_libcs.patch.  Replaced by upstream's
      __libc_initial flag.
    - Adjust glibc-rh819430.patch to upstream's gnulib merge of fnmatch.
    - Disable -Werror again due to GCC PR98512.
    - x86-64: Avoid rep movsb with short distance [BZ #27130]
    - aarch64: fix stack missing after sp is updated
    - nptl: Remove set*id, set*gid files which are not built
    - Drop nan-pseudo-number.h usage from tests
    - posix: Sync fnmatch with gnulib
    - Sync flexmember.h with gnulib
    - Sync intprops.h with gnulib
    - posix: Sync glob code with gnulib
    - posix: Sync regex code with gnulib
    - Move generic nan-pseudo-number.h to ldbl-96
    - Sync FDL from https://www.gnu.org/licenses/fdl-1.3.texi
    - Sync move-if-change from Gnulib
    - Update automatically-generated copyright dates
    - Update copyright dates not handled by scripts/update-copyrights.
    - Update copyright dates with scripts/update-copyrights
    - aarch64: use PTR_ARG and SIZE_ARG instead of DELOUSE
    - nonstring: Enable __FORTIFY_LEVEL=3
    - string: Enable __FORTIFY_LEVEL=3
    - Introduce _FORTIFY_SOURCE=3
    - Warn on unsupported fortification levels
    - powerpc: Use scv instruction on clone when available
    - powerpc: Runtime selection between sc and scv for syscalls
    - malloc: preserve errno on mcheck hooks [BZ #17924]
    - x86 long double: Add tests for pseudo normal numbers
    - x86 long double: Consider pseudo numbers as signaling
    - io: Remove xmknod{at} implementations
    - io: Remove xstat implementations
    - free: preserve errno [BZ#17924]
    - hurd: Accept including hurd/version.h
    - hurd: Add WSTOPPED/WCONTINUED/WEXITED/WNOWAIT support [BZ #23091]
    - support: Make support_process_state_wait wait less
    - hurd: set sigaction for signal preemptors in arch-independent file
    - hurd: Fix spawni SPAWN_XFLAGS_TRY_SHELL with empty argv
    - hurd: Try shell in posix_spawn* only in compat mode
    - Remove _ISOMAC check from <cpu-features.h>
    - x86: Remove the duplicated CPU_FEATURE_CPU_P
    - Partially revert 681900d29683722b1cb0a8e565a0585846ec5a61
    - x86 long double: Support pseudo numbers in isnanl
    - x86 long double: Support pseudo numbers in fpclassifyl
    - MTE: Do not pad size in realloc_check
    - tests-mcheck: New variable to run tests with MALLOC_CHECK_=3
    - elf: Account for glibc-hwcaps/ prefix in _dl_important_hwcaps
    - misc: Use __ferror_unlocked instead of ferror
    - s390x: Regenerate ulps
    - powerpc: Regenerate ulps
    - addmntent: Remove unbounded alloca usage from getmntent [BZ#27083]
    - <sys/platform/x86.h>: Add Intel LAM support
    - i386: Regenerate ulps
    - aarch64: update ulps.
    - aarch64: Add aarch64-specific files for memory tagging support
    - aarch64: Add sysv specific enabling code for memory tagging
    - linux: Add compatibility definitions to sys/prctl.h for MTE
    - malloc: Basic support for memory tagging in the malloc() family
    - elf: Add a tunable to control use of tagged memory
    - config: Allow memory tagging to be enabled when configuring glibc
    - alpha: Remove anonymous union in struct stat [BZ #27042]
    - add inputs to auto-libm-test-in yielding larger errors (binary64, x86_64)
    - m68k: fix clobbering a5 in setjmp() [BZ #24202]
    - iconv add iconv_close before the function returned with bad value.
    - iconv: use iconv_close after iconv_open
    - Fix buffer overrun in EUC-KR conversion module (bz #24973)
    - hurd: Make trampoline fill siginfo ss_sp from sc_uesp
    - Hurd: make sigstates hold a reference on thread ports
    - profil-counter: Add missing SIGINFO case
    - hurd: implement SA_SIGINFO signal handlers.
    - hurd: Fix ELF_MACHINE_USER_ADDRESS_MASK value
    - hurd: Note when the vm_map kernel bug was fixed
    - hurd: Also turn KERN_INVALID_ADDRESS to EINVAL
    - ieee754: Remove unused __sin32 and __cos32
    - ieee754: Remove slow paths from asin and acos
    - getenv: Move call to strlen to the branch it's used in.
    - Update kernel version to 5.10 in tst-mman-consts.py.
    - s390x: Require GCC 7.1 or later to build glibc.
    - malloc: Use __libc_initial to detect an inner libc
    - Replace __libc_multiple_libcs with __libc_initial flag
    - {nptl,htl}/semaphoreP.h: clean up
    - htl: Get sem_open/sem_close/sem_unlink support [BZ #25524]
    - pthread: Move semaphore initialization for open to semaphoreP.h
    - Mark __libc_freeres_fn as used [BZ #27002]
    - Update syscall lists for Linux 5.10.
    - htl: Add pshared semaphore support
    - hurd: Add LLL_PRIVATE and LLL_SHARED
    - hurd: Add __libc_open and __libc_close
    - htl: Add futex-internal.h
    - hurd: Add __lll_abstimed_wait_intr
    - hurd: make lll_* take a variable instead of a ptr
    - hurd: Rename LLL_INITIALIZER to LLL_LOCK_INITIALIZER
    - Use Linux 5.10 in build-many-glibcs.py.