[Gnash-dev] boost m4 macro

[Rob Savoye]

I just added the initial version of a macro to find Boost paths. The
results are used anywhere yet, but I'm curious too see how it breaks on
other people's installations so I can tweak it before we start using it.
Right now the only library it adds is boost_thread. I also added minimal
support to add AGG configure support as well while I was at it.

        - rob -