Ticket 48864 - Add cgroup memory limit detection to 389-ds
    
    Bug Description:  Previously our memory limits only check hardware
        limits and shell resource limits. However, we may be in a container
        like docker or lxc, and unable to detect these limits. This can lead
        to crash conditions or worse, especially with autosizing
        on import we may have conditions where the server may not
        even be able to install.
    
    Fix Description:  Add support for cgroup memory limit detection
        so that we can properly determine our resource availability regardless
        of lxc, docker, systemd or others.
    
    https://pagure.io/389-ds-base/issue/48864
    
    Author: wibrown
    
    Review by: mreynolds (Thanks!)