[boost] [multi_index] adding support for Compaq C++ for Tru64 Unix

Latest changes to Boost.Test have revealed that Boost.MultiIndex almost works for this compiler (toolset tru64cxx65), and I think the remaining problems are fixable. Is there any volunteer with local access to this compiler willing to help me in the process? Many thanks, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo