Smack: allow multiple labels in onlycap

Smack: allow multiple labels in onlycap

Smack onlycap allows limiting of CAP_MAC_ADMIN and CAP_MAC_OVERRIDE to
processes running with the configured label. But having single privileged
label is not enough in some real use cases. On a complex system like Tizen,
there maybe few programs that need to configure Smack policy in run-time
and running them all with a single label is not always practical.
This patch extends onlycap feature for multiple labels. They are configured
in the same smackfs "onlycap" interface, separated by spaces.

Change-Id: Ia95b93b4474669b7fd02926926e10b814b78405c
Signed-off-by: Rafal Krypa <r.krypa@samsung.com>
(cherry picked from commit c0a3794dfc6a153294fa90f6499a43c78a608047)