security: Add test on SELinux domains

Add a test suite that covers testing of the runtime domains
that process can exist in. The current test coverage ensures
that core processes like: init, eventd and zygote, are all
in a domain with a cardinality of one, and that their proctitle
is correct. Another test checks that the kernel threads, are indeed
kernel threads by verifying that vsize=0.

Change-Id: Id69c5a64b12c1f7f0fba9d1e050b93e6ca58000d