Generic solution for onlycap issues

Generic solution for onlycap issues

Once a process changes its smack label it may be unable to restore the original
one if onlycap is active and the new label is not in onlycap.

This commit provides a single class for handling process relabeling. The class
is able to restore the original process label even if onlycap is active. To do
so it stores the original onlycap value and original process label. The new
label is appended to current onlycap. When class is destroyed the old label and
old onlycap content is restored.

The drawback of this solution is that the relabeled process effectively gets
CAP_MAC_ADMIN.

The script for running ckm tests on onlycap has been removed.

All tests that do not directly test smack_set_label_for_self() use the new class
for process relabeling.

Change-Id: I0dda65fbd392f1b09061349061bdaf634efd9093