Cleaned up more unneeded functions and types in:

- src/basic/ioprio.h                     - removed
- src/basic/ring.h                       - removed

- src/basic/capability.[hc]              - cleaned
- src/basic/cgroup-util.[hc]             - cleaned
- src/basic/hostname-util.[hc]           - cleaned
- src/basic/path-util.[hc]               - cleaned
- src/basic/socket-util.h                - cleaned
- src/basic/strv.[hc]                    - cleaned
- src/basic/time-util.[hc]               - cleaned
- src/basic/unit-name.[hc]               - cleaned
- src/basic/util.[hc]                    - cleaned
- src/libelogind/sd-bus/bus-introspect.c - cleaned
- src/login/loginctl.c                   - cleaned
- src/login/logind-dbus.c                - cleaned
- src/login/logind.h                     - cleaned
- src/shared/conf-parser.[hc]            - cleaned