nsss

Use --enable-libc-includes when nsss improves (also fix shadow)
A circular dependency between nsss and s6 (at boot-time)
There is no test suite
The following definitions are missing in headers from nsss:

#include <features.h>

#define __NEED_size_t
#define __NEED_uid_t
#define __NEED_gid_t

#ifdef _GNU_SOURCE
#define __NEED_FILE
#endif

#include <bits/alltypes.h>

glibc includes a daemon called nscd, which caches the results of certain types of database lookups, and it is not particuarly useful unless there are a lot of users or groups, or when using a distributed authentication database like LDAP