cgroup: refactor for cgroups v2, much cleaner + unified hieararchy

Since the cgroups support in Finit is not yet officially released, we
decided to change the back-end to use cgroups v2 instead of the aging
and rather clumsy cgroups v1.  Even this initial refactor is a lot
easier to read and understand, more can still be done since there's
a lot of concepts, data values and the ilk that can now be shared
between different controllers.

Still ToDo: inotify for cgroup.events to clean up leaf nodes, which
            in cgroups v1 was handled by cgreaper.sh.  This is fixed
	    in the next commit in the series.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/finit.c

@@ -518,7 +518,6 @@ int main(int argc, char *argv[])
 	 */
 	cgroup_init();
 
-
 	/* Check and mount filesystems. */
 	fs_mount();