Ticket #47530 - dbscan on entryrdn should show all matching values
    
    Bug description:
    1) commit bded3015acdd5c71f05ceb10f10af220a02e6f74 was not a complete
       patch, which was failing in the case the entryrdn key is not given.
    2) Coverity 13190: Logically dead code
    
    Fix description:
    1) If an entryrdn key is not given, it sets DB_NEXT to the db flag and
       continues scanning the entryrdn index.
    2) The unnecessary checking 0 for the return code rc is removed.
    
    https://fedorahosted.org/389/ticket/47530
    
    Reviewed by rmeggins (Thank you, Rich!!)