Auto-sync with upstream branch master
    
    Upstream commit: ac0353af81a23535f517586a5d04427120a157ac
    
    - This removes libpthread as a separate shared object.  New programs
      will depend on the GLIBC_2.34 symbol version.  Upstream development
      brings in the following noteworthy bug fixes:
    - ppc64le: scv ABI error handling fails to check IS_ERR_VALUE (#1962971)
    - CVE-2021-27645 glibc: Use-after-free in addgetnetgrentX function in
      netgroupcache.c (#1932590)
    - Linking the main program with jemalloc causes sysconf to deadlock in
      audit mode (#1909920)