Releasing 4.7

Changelog:

    * Spawn: don't loop forever on ECHILD
    * Do not fail locking if there is a stale lockfile Tomas Mraz)
    * Use lckpwdf if prefix not set (Tomas Mraz)
    * Build: check correct DocBook version (Jan Tojnar)
    * Usermod: Print 'no changes' to stdout, not stderr (Serge Hallyn)
    * Add support for btrfs subvolumes for home (Adam Majer)
    * Fix chpasswd long line handling (Nathan Ruiz)
    * Use secure_getenv for gettime (Chris Lamb)
    * Make sp_lstchg reproducible (Chris Lamb)
    * Do not crash commonio_close if db file is not open (Tomas Mraz)
    * Don't flush nscd and sssd cache in read-only mode (Charlie Vuillemez)
    * French manpage update (Alban VIDAL)
    * Fix manpage defaults for SUB_UID/GID_COUNT (Tomas Mraz)
    * Sync po files from shadow.pot (Alban VIDAL)
    * Usermod: guard against unsafe chown of homedir contents (Tomas Mraz)
    * Add LASTLOG_UID_MAX to login.defs (Tomas Mraz)
    * new[ug]idmap file capabilities support (Giuseppe Scrivano and Christian Brauner)
    * Fix segfault in useradd (Tomas Mraz)
    * Coverity issues (Tomas Mraz)
    * Flush sssd caches (Jakub Hrozek)
    * Log UID in nologin (Vladimir Ivanov)
    * run pam_getenvlist after setup_env in su.c (Michael Vogt)
    * Support systems with only utmpx (A. Wilcox)
    * Fix unguarded ENABLE_SUBIDS code (Jan Chren (rindeal))
    * Update po/zh_CN translation (Lion Yang)
    * Create parent dirs for useradd -m (Michael Vetter)
    * Prevent usermod segv
    * Fix usermod crash (fariouche)