networkd: exit on idle

We will be woken up on rtnl or dbus activity, so let's just quit if some time has passed and that is the only thing that can happen.

Note that we will always stay around if we expect network activity (e.g. DHCP is enabled), as we are not restarted on that.

src/network/networkd.c

@@ -110,7 +110,7 @@ int main(int argc, char *argv[]) {
                   "READY=1\n"
                   "STATUS=Processing requests...");
 
-        r = sd_event_loop(m->event);
+        r = manager_run(m);
         if (r < 0) {
                 log_error_errno(r, "Event loop failed: %m");
                 goto out;