Auto-sync with upstream branch master
    
    Upstream commit: cba932a5a9e91cffd7f4172d7e91f9b2efb1f84b
    
    - nptl: Move nanosleep implementation to libc
    - Refactor nanosleep in terms of clock_nanosleep
    - nptl: Refactor thrd_sleep in terms of clock_nanosleep
    - math: enhance the endloop condition of function handle_input_flag
    - hurd: Remove lingering references to the time function
    - hurd: Use __clock_gettime in _hurd_select
    - login: Remove double-assignment of fl.l_whence in try_file_lock
    - nptl: Add missing placeholder abi symbol from nanosleep move
    - login: Acquire write lock early in pututline [BZ #24882]
    - Remove hppa pthreadP.h
    - sysdeps/clock_nanosleep: Use clock_nanosleep_time64 if avaliable
    - Fix array bounds violation in regex matcher (bug 25149)
    - support: Add support_set_small_thread_stack_size
    - linux: Reduce stack size for nptl/tst-thread-affinity-pthread
    - y2038: linux: Provide __ppoll64 implementation
    - Declare asctime_r, ctime_r, gmtime_r, localtime_r for C2X.
    - support: Add xsetlocale function
    - libio/tst-fopenloc: Use xsetlocale, xfopen, and xfclose
    - Fix clock_nanosleep when interrupted by a signal
    - slotinfo in struct dtv_slotinfo_list should be flexible array [BZ #25097]