Initial support for cgroups

Similar to how systemd creates cgroups for all services, for purposes of
tracking, Finit now does the same.  We also mount all available cgroups
in the /sys/fs/cgroup namespace.

This patch adds support for grouping processes in logical cgroups, like
systemd, and an `initctl ps` command to list the hieararchy.

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

src/Makefile.am

@@ -10,6 +10,7 @@ endif
 
 bin_PROGRAMS       = logit
 sbin_PROGRAMS      = finit initctl reboot
+pkglibexec_SCRIPTS = cgreaper.sh
 if WATCHDOGD
 pkglibexec_PROGRAMS = watchdogd
 endif
@@ -17,7 +18,7 @@ endif
 logit_SOURCES      = logit.c
 logit_CFLAGS       = -W -Wall -Wextra -Wno-unused-parameter -std=gnu99
 
-finit_SOURCES      = api.c					\
+finit_SOURCES      = api.c	cgroup.c	cgroup.h	\
 		     cond.c	cond-w.c	cond.h		\
 		     telinit.c					\
 		     conf.c	conf.h				\