[CRIU] zdtm cwd test acts strangly

[Ruslan Kuprieiev]

So, Andrew and I did some investigation and here is what we came up with.

The problem is that zdtm doesn't set additional groups when running
tests. So, it sets uids and gids to some non-root values, but additional
groups remain untouched.

When running tests from tty(login as root) you don't get any additional
groups at all, but on pty I used su to became root, and, as it
turned out, it sets additional groups to "0". So, when I'm running tests
from tty, cwd00 can't chdir to /root/git/criu/test/zdtm/live/static
because it has no access to /root. But when running from pty, 0 in
additional groups provides access to /root.

The solution is to make zdtm set additional groups too. I'll send patch
ASAP.

Thanks! =)