Ticket 386 - large memory growth with ldapmodify(heap fragmentation)
    
    Bug Description:  large entry cache can lead to significant memory fragmentation.
    
    Fix Description:  On linux you can disable "fastbins", or modify the size of the bins
                      using mallopt(), which can help reduce the memory fragmentation.
    
    https://fedorahosted.org/389/ticket/386
    
    Reviewed by: richm(Thanks Rich!)