util: vircgroupv2: use any controller to create thread directory
util: vircgroupv2: use any controller to create thread directory

The assumption that CPU controller would be always enabled is wrong, we
should use any available controller to create a new sub-cgroup.

Signed-off-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

crobinso/libvirt,zippy2/libvirt,eskultety/libvirt,nertpinx/libvirt,libvirt/libvirt,olafhering/libvirt,jardasgit/libvirt,andreabolognani/libvirt,zippy2/libvirt,jardasgit/libvirt,jardasgit/libvirt,andreabolognani/libvirt,eskultety/libvirt,fabianfreyer/libvirt,crobinso/libvirt,nertpinx/libvirt,jardasgit/libvirt,crobinso/libvirt,fabianfreyer/libvirt,crobinso/libvirt,andreabolognani/libvirt,eskultety/libvirt,fabianfreyer/libvirt,olafhering/libvirt,nertpinx/libvirt,andreabolognani/libvirt,libvirt/libvirt,jfehlig/libvirt,libvirt/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,jfehlig/libvirt,jardasgit/libvirt,zippy2/libvirt,libvirt/libvirt,eskultety/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,andreabolognani/libvirt,nertpinx/libvirt,olafhering/libvirt,jfehlig/libvirt,olafhering/libvirt,zippy2/libvirt,eskultety/libvirt