xtrn.cpp mods for dosemu2

Can you please add the following to xtrn.cpp around line 1528 to support dosemu2. Not sure why these weren't included in the first place.

                    {(char*)"NODEDIR", cfg.node_dir},
                    {(char*)"EXECDIR", cfg.exec_dir},
                    {(char*)"DATADIR", cfg.data_dir},
                    {(char*)"XTRNDIR", xtrndir},