cgroup: don't worry if a cgroup already exists
cgroup: don't worry if a cgroup already exists

Signed-off-by: Andrew Vagin <74c05afa918858348d6db8037d82fa8124870113@openvz.org>

xemul/libct,avagin/libct,xemul/libct,hallyn/libct,avagin/libct,hallyn/libct,hallyn/libct,xemul/libct,avagin/libct,xemul/libct