Ticket #305 - Certain CMP operations hang or cause ns-slapd to crash
    
    Bug Description:  There is a potential double free in cos_cache_query_attr().  If you
                      run concurrent search or compares its very easy to crash the
                      server in this code
    
    Fix Description:  Moved the DN normalization into the cache rebuilding code.
    
    https://fedorahosted.org/389/ticket/305
    (cherry picked from commit 142c8f0fe93d77990df8ce991a8020918276ddd8)