In case of error inside collect_cgroups we need

- @ctls list has been spliced into @cs->ctls so we cant just free it,
   but rather use put_ctls on @cs->ctls

- delete @cs->l from global @cg_sets list before free it
Signed-off-by: Cyrill Gorcunov <gorcunov@virtuozzo.com>
Reviewed-by: Andrew Vagin <avagin@openvz.org>
Acked-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>