dbus: import struct unit_info from systemctl

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
dbus: introduce parse_unit_info

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
systemctl: use parse_unit_info

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
systemd-analyze: rewrite in C.

Written by Peeters Simon <peeters.simon@gmail.com>.
Makefile stuff and cleaned up a bit by Auke Kok <auke-jan.h.kok@intel.com>.
Some code inspired by Marc-Antoine Perennou <Marc-Antoine@Perennou.com>.
move systemctl dot to systemd-analyze depgraph