Auto-sync with upstream branch master
    
    Upstream commit: 4c38c1a229bc3628269ad98bd7e8d31d118d91f6
    
    - Drop glibc-revert-fxstat-compat.patch; applied upstream.
    - Drop glibc-revert-mknod-compat.patch; applied upstream.
    - powerpc64le: Add glibc-hwcaps support
    - x86: Adjust tst-cpu-features-supports.c for GCC 11
    - x86: Set RDRAND usable if CPU supports RDRAND
    - elf: Add missing <stddef.h> header to elf/dl-hwcaps.h
    - lowlevellock-futex: Remove not used macros
    - futex: Remove not used futex_reltimed_wait{_cancelable}
    - y2038: Convert gai_suspend to support 64 bit time
    - symbols: Add defines for libanl's libanl_hidden_{def|proto}
    - x86_64: Add glibc-hwcaps support
    - elf: Add glibc-hwcaps subdirectory support to ld.so cache processing
    - elf: Process glibc-hwcaps subdirectories in ldconfig
    - elf: Implement tail merging of strings in ldconfig
    - elf: Implement a string table for ldconfig, with tail merging
    - elf: Add extension mechanism to ld.so.cache
    - elf: Add endianness markup to ld.so.cache (bug 27008)
    - elf: Add glibc-hwcaps support for LD_LIBRARY_PATH
    - elf: Synchronize <elf.h> section header flags with binutils
    - x86: Fix THREAD_SELF definition to avoid ld.so crash (bug 27004)
    - htl: Add hidden def for __pthread_create/detach
    - manual: Clarify File Access Modes section and add O_PATH
    - htl: Add missing symbols
    - Revert "linux: Move xmknod{at} to compat symbols"
    - Revert "linux: Move {f}xstat{at} to compat symbols"
    - elf.h: Fix spelling of EM_TILE64 comment
    - nptl: Fix __futex_clocklock64 return error check [BZ #26964]
    - powerpc64le: ifunc select *f128 routines in multiarch mode
    - y2038: Convert aio_suspend to support 64 bit time
    - Fix typo in NEWS file
    - nptl: Add EOVERFLOW checks for futex calls
    - nptl: Fix PTHREAD_PRIO_PROTECT timed lock
    - sh: Add sh4 fpu Implies folder
    - io: nftw/ftw: Fix stack overflow with large nopenfd [BZ #26353]
    - elf: Introduce enum opt_format in the ldconfig implementation
    - support: Add support_copy_file
    - NEWS entry for commit b4f020c9b408fb3d1d3d4901c4a71839145f8791
    - timezone: Change zdump installation to bin directory
    - nptl: Return EINVAL for invalid clock for pthread_clockjoin_np
    - nptl: Return EINVAL for pthread_mutex_clocklock/PI with CLOCK_MONOTONIC [BZ #26801]
    - nptl: Replace lll_futex_wake with futex-internal.h
    - nptl: Replace lll_futex_supported_clockid with futex-internal.h
    - nptl: Replace lll_futex_{timed_}wait by futex-internal.h
    - nptl: Replace lll_timedwait with __futex_abstimed_wait64
    - nptl: Replace __futex_clocklock_wait64 with __futex_abstimed_wait64
    - nptl: Remove _futex_clock_wait_bitset64
    - nptl: Consolidate __futex_abstimed_wait_{cancelable}64
    - nptl: Extend __futex_abstimed_wait_cancelable64 comment
    - nptl: Remove clockwait_tid
    - nptl: Remove futex_wait_cancelable
    - nptl: Remove unused internal futex functions
    - Mark mtrace tests UNSUPPORTED if bug-ga2.mtrace or tst-leaks2.mtrace are missing
    - elf: Fix uninitialized variable for _dl_write
    - powerpc: Make PT_THREAD_POINTER available to assembly code
    - Use libnss_files.so for tests posix/bug-ga2 and resolv/tst-leaks2 [BZ #26821]
    - hurd report-wait: Fix stpcpy usage
    - hurd S_msg_report_wait: Fix detecting fd ports
    - hurd S_msg_report_wait: Fix reporting ports
    - hurd: Fix strcpy calls
    - hurd: Fix _S_msg_get/set_env_variable prototype
    - hurd: Enable using ifunc
    - Add {,sysdep-}ld-library-path make variable
    - nptl: Move stack list variables into _rtld_global
    - hurd: let _dl_argv and __libc_stack_end be relro
    - hurd: Remove some remnants of cthreads
    - nanosleep: Pass NULL when rem == NULL on ports with __TIMESIZE != 64
    - y2038: Convert thrd_sleep to support 64 bit time
    - y2038: Convert mtx_timedlock to support 64 bit time
    - y2038: Convert cnd_timedwait to support 64 bit time
    - hurd: Drop CLOCK_MONOTONIC change which slipped in
    - hurd: make ptsname fail with ENOTTY on non-master-pty
    - mach: Add missing assert.h include
    - hurd: break relocation loop between libc.so and lib{mach,hurd}user.so
    - Remove obsolete defines for HPUX support from fcntl.h and update O_NONBLOCK.
    - Remove tls.h inclusion from internal errno.h
    - nptl: Eliminate <smp.h> and __is_smp
    - powerpc: Eliminate UP macro conditionals
    - x86: Remove UP macro.  Define LOCK_PREFIX unconditionally.
    - alpha: Remove UP preprocessor conditionals
    - hurd: Make sure signals get started
    - hurd: initialize libpthread before starting the signal thread
    - hurd: Make _hurd_libc_proc_init idempotent
    - powerpc: Add optimized stpncpy for POWER9
    - powerpc: Add optimized strncpy for POWER9
    - Don't use nested function in test-ffs
    - Use __builtin___stpncpy_chk when available
    - tests: Remove NULL check for an array
    - hurd: Move {,f,l}xstat{,at} and xmknod{at} to compat symbols
    - hurd: Notify the proc server later during initialization
    - htl: Initialize later
    - htl: Keep thread signals blocked during its initialization
    - htl: Fix spurious symbols in namespaces
    - Use O_CLOEXEC in sysconf [BZ #26791]
    - struct _Unwind_Exception alignment should not depend on compiler flags
    - hurd: keep only required PLTs in ld.so
    - hurd: Add missing startup calls
    - riscv: Get cache information through sysconf
    - RISC-V: Add _dl_start_user.