Auto-sync with upstream branch master,
    
    Upstream commit: 0487ebed2278b20971af4cabf186fd3681adccf0
    
    - nptl: Add more missing placeholder abi symbol from nanosleep move
    - sysdeps/riscv/start.S: rename .Lload_gp to load_gp (bug 24376)
    - y2038: linux: Provide __timer_settime64 implementation
    - y2038: linux: Provide __timer_gettime64 implementation
    - timer: Decouple x86_64 specific timer_settime from generic Linux implementation
    - timer: Decouple x86_64 specific timer_gettime from generic Linux implementation
    - time: Introduce glibc's internal struct __itimerspec64
    - Correct range checking in mallopt/mxfast/tcache [BZ #25194]
    - misc/test-errno-linux: Handle EINVAL from quotactl
    - <string.h>: Define __CORRECT_ISO_CPP_STRING_H_PROTO for Clang [BZ #25232]
    - build-many-glibcs.py: Move sparcv8 to extra_glibcs