Fron c3bd0019 on instead of creating the following path for
cgroups:

  /sys/fs/cgroupX/$name.libvirt-$driver

we generate rather more verbose one:

  /sys/fs/cgroupX/$driver-$id-$name.libvirt-$driver

where $name is optional and included iff contains allowed chars.
See original commit for more reasoning. Now, problem with the
original commit is that we are unable to start any LXC domain
after it. Because when starting LXC container, the CGroup layout
is created by our lxc_controller process and then detected and
validated by libvirtd. The validation is done by trying to match
detected layout against all the possible patterns for cgroup
paths that we've ever had. And the commit in question forgot to
update this part of the code.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>