[boost] boost.filesystem on HPUX

The boost.filesystem does not compile succesfully on HPUX/itanium with aCC because (in bbv1) the function readdir_r is not known. It compiles fine though if the flag '-mt' (to enable multi-threading) is added to the command-line. Does anybody now any other flag that might influence this? Is it normal (never used readdir_r myself) that it is only defined in multi-threading-mode? Should we instruct bbv1 to compile the boost.filesystem always with the -mt flag on hpux ? toon