Switch default database to sqlite (#1818910)
    
    Newly created databases will be sqlite unless overridden in configuration.
    
    If BDB database is detected at %posttrans of rpm itself, it's flagged
    for rebuild in the next reboot. This will serve two purposes: the primary
    objective is obviously to convert to configured (ie sqlite) format,
    but as a secondary side-effect, any remaining BDB databases will get
    a much needed maintenance rebuild from time to time.