oci: Use variable for directory perms.
oci: Use variable for directory perms.

Create dirMode to make creating directories consistent.

Signed-off-by: James O. D. Hunt <348fbaadfbada55ea105602bf5609e23ac1c4898@intel.com>

containers/virtcontainers,wcwxyz/virtcontainers,containers/virtcontainers,wcwxyz/virtcontainers,wcwxyz/virtcontainers