lslogins: improve nologins and shadow usage

 * fix coding style
 * don't require shadow entries
 * check for /var/run/nologin

Signed-off-by: Karel Zak <kzak@redhat.com>
lslogins: remove --sort-by-name

If we really need a sort functionality hardcoded into lslogins(1) then we need
a generic sort options (like for lsblk,--sort <column>).

Note that it seems that "lslogins | sort --key <col>" is good enough for now as
lslogins(1) does not convert any data to human readable non-precise format (like
for example lsblk SIZE column etc.).

Signed-off-by: Karel Zak <kzak@redhat.com>
build-sys: add sys-utils/uname26.8 to gitignore

Reported-by: Sami Kerola <kerolasa@iki.fi>
Signed-off-by: Karel Zak <kzak@redhat.com>
lslogins: clean up password hash check

 * rename to PWD-* column names
 * add PWD-DENY for accounts where is no possible to login by password
 * PWD-LOCK (was LOCKED) checks for valid but locked pawwords
 * LOGIN renamed to USER

Signed-off-by: Karel Zak <kzak@redhat.com>
lslogins: cleanup time formats

Signed-off-by: Karel Zak <kzak@redhat.com>
lslogins: fix nologins check

Signed-off-by: Karel Zak <kzak@redhat.com>
lslogins: cleanup usage()

Signed-off-by: Karel Zak <kzak@redhat.com>
lslogins: improve COL_PWD_WARN and COL_NPROCS desc

Signed-off-by: Karel Zak <kzak@redhat.com>
lslogins: cleanup -a output

Signed-off-by: Karel Zak <kzak@redhat.com>
lslogins: cleanup default outputs

Signed-off-by: Karel Zak <kzak@redhat.com>
lslogins: cleanup some command line options

Signed-off-by: Karel Zak <kzak@redhat.com>
lslogins: fix pretty-print columns

Signed-off-by: Karel Zak <kzak@redhat.com>