Spatializer audio filter, work for Google Summer of Code, by Isaac Biodun Osunkunle: osunkunle --- gmail.com
This is the first part of his work.

Use libav*-uninstalled.pc to get the ldflags for ffmpeg when we use --with-ffmpeg-tree to link statically

Can't test if it now works (no GNOME here)

safe side

(jb, pdherbemont are missing by the way)