add cgroup cleanup support

This adds the ability to kill all processes within a service's cgroup
when that service is stopped or restarted.

sh/runscript.sh.in

@@ -302,6 +302,8 @@ while [ -n "$1" ]; do
 				then
 					"$1"_post || exit $?
 				fi
+				[ "$(command -v cgroup_cleanup)" = "cgroup_cleanup" ] && \
+					cgroup_cleanup
 				shift
 				continue 2
 			else