Previously we would fail in some parts of the code if we did not have a
premade configuration, now we use any code that was marked as Linux, BSD and
Solaris as our basis in order to support building unknown Unix systems.
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.
* Revert changes to programs/dtsearchpath/libCliSrv/UnixEnv.C
introduced by c3cb5b8aa6
that could have produced disappearing Application Manager
icons on FreeBSD
* Introduce SearchPath:useSystemPath() virtual method to tell
dtsearchpath to leave some environment variables alone.
It is currently overriden for FreeBSD only if the MANPATH
is empty (system default). Other operating systems
might want to override it if they prefer to have distribution
specific control of a search path in effect.
* Symlink /usr/dt/share/man to /usr/dt/man for FreeBSD
This allows dtsearchpath to actually include /usr/dt/man
in the MANPATH when MANPATH override is in effect.
