Ticket 73, 67, 40 - Replace nunc-stans datastructures with libsds
    
    Bug Description:  For nunc-stans to be portable and adopted by Directory
    Server more broadly, we need to be able to run it on a variety of platforms
    and architectures.
    
    Additionally, the lfds build integration we have is messy and generally
    causes portability issues.
    
    Fix Description:  Libsds is written to address this. It contains an integrated
    build of lfds710. It correctly detects if on x86_64 and will build the lock
    free variants, and will correctly fall back to a lock based queue on
    unsupported arches.
    
    This resolves not only our portability and build complexitiy issues, but also
    our architecture support problem.
    
    Another signifigant benefit is the reduction in code to nunc-stans. Previously
    we had to implement and wrap a number of datastructures in nunc-stans, but
    now this removes that dependence out to SDS.
    
    This commit is the first stage, ifdefing out the LFDS components, and integrating
    SDS in their place.
    
    The second commit will remove all LFDS components and code from the source tree.
    
    https://pagure.io/nunc-stans/issue/73
    https://pagure.io/nunc-stans/issue/67
    https://pagure.io/nunc-stans/issue/40
    
    See also: https://pagure.io/libsds
    
    Author: wibrown
    
    Review by: mreynolds (Thanks!)