Ticket 49119 - Cleanup configure.ac options and defines
    
    Bug Description:  We have a lot of legacy in files like configure.ac.
    We have options that we default to that aren't set correctly, options
    we never use now, and more.
    
    Fix Description:  Clean up some of these options. Remove defines
    and substitutions that were never used. Cleanup some headers to
    standardise their use of certain defines.
    
    https://pagure.io/389-ds-base/issue/49119
    
    Author: wibrown
    
    Review by: mreynolds (Thanks!)