Auto-sync with upstream branch master
    
    Upstream commit: 088e9625378f25607acff3daf7a79cbdee497043
    
    - x86: Rename readelflib.c
    - nsswitch: use new internal API (callers)
    - nsswitch: user new internal API (tests)
    - nsswitch: use new internal API (core)
    - nss: Implement <nss_database.h>
    - <nss_action.h>: New abstraction for combining NSS modules and NSS actions
    - nss: Introduce <nss_module.h>
    - Add scripts/move-symbol-to-libc.py