[bind10-dev] identify ext/asio

[Evan Hunt]

> A related question: will we continue including a copy of ASIO in tar
> balls?

I think we probably should.  Most of the world has gone to boost::asio, so
I doubt if many OS distributions will be including the headers we need--
and I'd rather not require people to fetch multiple tarballs from multiple
locations to build BIND 10.

                                eh