test: add selinux00 test

This tests if CRIU can restore a process with the same policy as during
checkpointing.

The test selinux00 is started and if SELinux is available the test
process moves itself to another process context. To make this possible
either a new SELinux policy needs to be available containing:

https://github.com/fedora-selinux/selinux-policy/commit/2d537cabbb2df614ea598ac20873c653cbf271a8



Or for a short time SELinux is switched to permissive mode.

The correct SELinux setup is done by zdtm/static/selinux00.checkskip and
zdtm/static/selinux00.hook and after the test the previous SELinux
policy state is restored.

After the test case is restored the test case checks if it still has the
same SELinux process context as before. If not the test cases fails.

Signed-off-by: Adrian Reber <areber@redhat.com>