cgroup.c: fix a iwatcher initializing issue
cgroup.c: fix a iwatcher initializing issue

iwatcher of cgroup needs to be initialized earlier before any
cgroup_add functions being called.

Signed-off-by: Ming Liu <070ee461bca4578ddd34d91eec07d1f455f3cdee@gmail.com>

troglobit/finit,troglobit/finit