[tlbuild] dvipdfmx, asymptote

[Karl Berry]

1) As expected, I just needed to tweak one line in dvipdfmx.  It's not
   critical to rebuild, but if you're up for it, go for it.  That should
   be the only changed binary.

2) asymptote 1.83 is released and I've updated utils/asymptote.  Those
   of you who are building asy, please use this.  John may well make
   another release, but this is supposed to be pretty stable.
   
   Vladimir, please do the i386-linux and x86_64-linux builds for asy as
   you did before, ok?

Thanks,
Karl