[tlbuild] xetex not being built

[Karl Berry]

Hi Jukka,

        lambda mf-nowin omega oxdvi texlua texluac xelatex xetex

As Peter wrote, omega, lambda, and oxdvi being missing is intentional.

I don't get mf-nowin either, but we do want that, so I guess it needs to
be restored somewhere.  Peter, help please?  It seems mf is mf-nowin
now, judging by the shared libraries -- no X.  We want mf to be the
interactive display-capable version.  Knuth sent a bug report
excoriating us about that at one point.

texlua and texluac are missing links to luatex.  They are also missing
for me.  I'll try to figure out a good place to add them.

Thanks,
Karl