Ticket 49053 - Enable flto for DS
    
    Bug Description:  Link Time Optimisation allows GCC to perform
    broader and more substantial improvements to our code. This is
    described https://gcc.gnu.org/onlinedocs/gccint/LTO-Overview.html
    
    Fix Description:  To enable LTO, there were a number of errors
    exposed on libldaputil related to the use of a callback struct.
    However, because of the current definition of INTLDAPU, this
    meant that the macros and ldap access vector were never accessed.
    This cleans up the struct and remove the macros, which resolves
    the issue with LTO building.
    
    https://gcc.gnu.org/onlinedocs/gccint/LTO-Overview.html
    
    Author: wibrown
    
    Review by: mreynolds (Thanks!)