Prevent to add multiple versions of the same controller to mount_table
Prevent to add multiple versions of the same controller to mount_table

This patche add a test to cgroup_init function, which prevent to add
multiple records for the same controller (this is a problem eg. in
cgroup_get_cgroup function - which looks to mount table and add all
relevant controllers using cgroup_add_controller function and when the
function calls cgroup_add_cgroup function twice on the same controller,
it returns error so the result is cgroup_get_cgroup failed).

Signed-off-by: Ivana Varekova <2e3918a0a366ea7e658a2062ab582c898a7e1b1b@redhat.com>
Signed-off-by: Dhaval Giani <9e8a88f272eaf8af1eb7757146d1fb3d7f128182@linux.vnet.ibm.com>

rafalmiel/libcg,jrfastab/Linux-cgdcbxd,rafalmiel/libcg,jrfastab/Linux-cgdcbxd,rafalmiel/libcg,jrfastab/Linux-cgdcbxd,jrfastab/Linux-cgdcbxd,rafalmiel/libcg