[tlbuild] asy 2.16 sources committed for building

[Karl Berry]

John has released asymptote 2.16, and I've updated the sources in TL.
Those of you who are planning to build it, please give it a try.

I ran into an unnecessary remake of the .pdf documentation, but had no
other problems, with the usual recipe:
http://tug.org/texlive/build.html#asymptote

I'll wait to commit the i386-linux binary and new support files until
(my) tomorrow.

This is the last thing to do before the final freeze and images, so
please get to it ASAP.

Thanks,
Karl