Get rid of our reimplementation of basename

The only problem is that libgen.h #defines basename to point to it's
own broken implementation instead of the GNU one. This can be fixed
by #undefining basename.
systemctl: allow globbing in list-<whatever> commands

It is nicer to say 'systemctl list-units ssh\*' then to use grep,
because colouring is preserved and it is easier to match just against
the unit name.