These are just minor tweaks to make sure the 'make install' part does
what it is supposed to do. I also removed some commented code in the
dtmail Makefile related to SunOS, as that is not currently suppoerted
anyway.
Also, restructure some of the dependencies in the lib/tt binaries. We
will link with libtt (which will include libtirpc as a dependency),
and XTOOLLIB - all the right X11 stuff without needing to add it to
every OS. Removed several uneeded OS specializations ("if LINUX",
etc) as a result.
