Auto-sync with upstream branch master
    
    Upstream commit: 27f8864bd41f0f1b61e8e947d9a030b1a0d23df9
    
    - x86: Update F16C detection [BZ #26133]
    - Fix avx2 strncmp offset compare condition check [BZ #25933]
    - nptl: Remove now-spurious tst-cancelx9 references
    - x86_64: Use %xmmN with vpxor to clear a vector register
    - x86: Correct bit_cpu_CLFLUSHOPT [BZ #26128]
    - powerpc64le: refactor e_sqrtf128.c
    - Update syscall-names.list for Linux 5.7.
    - ieee754/dbl-64: Reduce the scope of temporary storage variables
    - manual: Add pthread_attr_setsigmask_np, pthread_attr_getsigmask_np
    - ld.so: Check for new cache format first and enhance corruption check
    - hurd: Fix __writev_nocancel_nostatus
    - hurd: Make send* cancellation points
    - htl: Enable more cancellation tests
    - hurd: Make write and pwrite64 cancellation points
    - htl: Fix cleanup support for IO locking
    - htl: Move cleanup stack to variable shared between libc and pthread
    - htl: initialize first and prevent from unloading
    - htl: Add noreturn attribute on __pthread_exit forward
    - hurd: Make recv* cancellation points
    - powerpc: Automatic CPU detection in preconfigure
    - Use Linux 5.7 in build-many-glibcs.py.
    - htl: Enable more cancel tests
    - htl: Fix linking static tests by factorizing the symbols list
    - Add "%d" support to _dl_debug_vdprintf
    - aarch64: MTE compatible strlen
    - aarch64: MTE compatible strchr
    - aarch64: MTE compatible strchrnul
    - AArch64: Merge Falkor memcpy and memmove implementations
    - hurd: document that gcc&gdb look at the trampoline code
    - pthread: Move back linking rules to nptl and htl
    - htl: Enable more tests
    - htl: Fix registration of atfork handlers in modules
    - htl: Fix tls initialization for already-created threads
    - hurd: Make read and pread64 cancellable
    - hurd: Fix unwinding over interruptible RPC
    - htl: Enable but XFAIL tst-flock2, tst-signal1, tst-signal2
    - hurd: XFAIL more tests that require setpshared support
    - hurd: Briefly document in xfails the topics of the bugzilla entries
    - htl: Enable more tests
    - htl: Add sem_clockwait support
    - htl: fix register-atfork ordering
    - hurd: Fix hang in _hurd_raise_signal from pthread_kill
    - hurd: Reject raising invalid signals
    - hurd: fix clearing SS_ONSTACK when longjmp-ing from sighandler
    - hurd: Add pointer guard support
    - hurd: Add stack guard support
    - dl-runtime: reloc_{offset,index} now functions arch overide'able
    - powerpc64le: add optimized strlen for P9
    - powerpc64le: use common fmaf128 implementation