check/zdtm: Introduce fine-grained feature testing

Right now we state that CRIU works on 3.11 and above kernels and, at the
same time, have support for a couple of new features like aio, tun, timerfd
etc. available in later kernels. Since these new features do not break
generic operations we do not require them in the kernel strictly.

However, in the zdtm tests it's very important to know exactly what can
and what cannot be tested. Right now this is done in a tough manner -- if
the kernel is not 3.11 or criu check fails for _any_ reason we treat the
kernel as being "bad" and throw out a set of tests.

I propose to test some individual features and form the list of tests
in a more fine-grained manner.

This patch only fixes the AIO, mnt_id, tun and posix-timers tests. Next
I will add checks and fixes for user-namespaces tests.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Andrew Vagin <avagin@parallels.com>