[CRIU] mount namespace in criu

[Pavel Emelyanov]

Hi guys.

An first step of the subj is on repo. All zdtms are passing OK. Only virtual proc
and sysfs filesystems are supported, no bindmounts for now and no fixes for
paths-vs-namespaceroot in the code. Just plain simple tree recreation.

Andrey, there's a problem with our test_init in zdtm -- it uses system() call
to run make stop, but strictly speaking this doesn't work -- this test_init
stuff doesn't have any fds open (image is empty) and if on restore I explicitly
close them (we should do it) the system() just fails :(

Let's discuss this tomorrow.

Thanks,
Pavel