Ticket 49392 - memavailable not available
    
    Bug Description:  On certain linux platforms memAvailable is
    not actually available! This means that the value was 0, so
    cgroup max was read instead, setting the system ram to:
    
    9223372036854771712
    
    That's a bit excessive, and can cause memory allocations to fail.
    
    Fix Description:  If memavail can't be found, fall back to
    memtotal instead.
    
    https://pagure.io/389-ds-base/issue/49392
    
    Author: wibrown
    
    Review by: mreynolds (Thanks!)