Auto-sync with upstream branch master
    
    Upstream commit: b881f1efcd1b30c2afab3599b41ce9cd4864c823
    
    - elf: Add new LoongArch reloc types (110 to 126) into elf.h
    - build-many-glibcs.py: Add s390 --disable-multi-arch / multi-arch configurations.
    - sparc: Treat the version field in the FPU control word as reserved
    - Implement setcontext/getcontext/makecontext/swapcontext for Hurd x86_64
    - Use proc_getchildren_rusage when available in getrusage and times.
    - Linux: Switch back to assembly syscall wrapper for prctl (bug 29770)
    - i386: Use generic memrchr in libc (bug 31316)