[opus] build opus codec with visual studio 2005

[Timothy B. Terriberry]

Luca Fancellu wrote:
> i've downloaded source code fromhttp://www.opus-codec.org/downloads/but
> in the tarball there is only one project for visual studio 2010, it
> builds well but if i use .lib on visual studio 2005 they won't work...
> Anyone knows how to compile with visual studio 2005?

You'll have to make new project files for MSVC 2005. Hopefully it should 
not be too difficult. We've tried to set up the directory structure to 
allow multiple project files for multiple MSVC versions to sit 
side-by-side without conflict, but no one has contributed back project 
files for other versions yet.