[tlbuild] asy 1.96 in sources

[Karl Berry]

    What should we do for TL2010? To back the asymptote build with TL2010
    pretest install?

I think so, yes.  The texi2dvi stuff doesn't matter -- we don't rebuild
the asy documentation -- but kpsewhich is crucial.  That's what makes
asy self-locating in our builds.  (I haven't checked the current source
to see if the configure check implies not using kpsewhich, but that's
what I'd expect.)

Thanks,
k