[tldistro] texmf.cnf and compile-time paths

[Karl Berry]

The binaries included in "native" TeX Live have previously ended up
including the personal build-time directory names in the compile-time
paths, due to the torturous procedure of creating kpathsea/paths.h.

I've just simplified that process, so that the source kpathsea/texmf.cnf
is now a slave copy of the live Master/web2c/texmf.cnf (similar to
fmtutil.cnf I did yesterday), there is no kpathsea/texmf.in file any
more, and all the compile-time paths have the $TEXMF... variables
expanded to /nonesuch/directory/names, to make it clear that they are
useless.

I also removed /.$TETEXDIR from the default TEXMFCNF setting, since,
well, we are not teTeX.

I know all you guys had to mess with all this stuff anyway to get TeX to
find your files.  Sorry about having to redo all your patches, but I
dearly hope that this new scheme will be more comprehensible.  At least
it is to me :).  (The world was a lot different when I devised with the
original scheme 15-odd years ago ... it all made sense at the time. :)

If there are further changes in this area that would ease the work for
the distro integration, let me know.

karl