libcgroup: Modify the APIs to use the namespace
libcgroup: Modify the APIs to use the namespace

Since every API builds its patch via build_path, updating that
function should be enough.

Changes from v1:
1. Append the namespace only if it is defined. This will remove an
additional "/" which would be introduced otherwise.

Signed-off-by: Dhaval Giani <9e8a88f272eaf8af1eb7757146d1fb3d7f128182@linux.vnet.ibm.com>

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