Sync with upstream branch release/2.34/master
    
    Upstream commit: 4ed990e5b97a61f29f929bdeb36c5b2abb547a64
    
    - Add MADV_POPULATE_READ and MADV_POPULATE_WRITE from Linux 5.14 to
      bits/mman-linux.h
    - Update kernel version to 5.14 in tst-mman-consts.py
    - Update syscall lists for Linux 5.14
    - Use Linux 5.14 in build-many-glibcs.py
    - Fix failing nss/tst-nss-files-hosts-long with local resolver
    - iconvconfig: Fix behaviour with --prefix [BZ #28199]
    - nptl: Fix race between pthread_kill and thread exit (swbz#12889, #1994068)
    - nptl: pthread_kill, pthread_cancel should not fail after exit
      (swbz#19193, #1994068)
    - support: Add support_wait_for_thread_exit
    - MIPS: Setup errno for {f,l,}xstat
    - x86-64: Use testl to check __x86_string_control
    - elf: Fix missing colon in LD_SHOW_AUXV output (swbz#28253, #1995648)
    - librt: add test (swbz#28213, #1994264)
    - CVE-2021-38604: fix NULL pointer dereference in mq_notify
      (swbz#28213, #1994264)
    - Linux: Fix fcntl, ioctl, prctl redirects for _TIME_BITS=64 (bug 28182)
    - iconv_charmap: Close output file when done
    - copy_and_spawn_sgid: Avoid double calls to close()
    - gaiconf_init: Avoid double-free in label and precedence lists
    - gconv_parseconfdir: Fix memory leak
    - ldconfig: avoid leak on empty paths in config file