Revert "util: cgroup: use VIR_AUTOPTR for aggregate types"
    
    This reverts commit dd47145aaad780cde0f1d67cf6a85737c0292418.
    
    Turns out, our code relies on virCgroupFree(&var) setting
    var = NULL.
    
    Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
    Reviewed-by: Pavel Hrdina <phrdina@redhat.com>