For some build-environments where you want tight control over which dependencies
that are linked statically / dynamically and how these libraries are configured,
some additional measures are needed.

On systems with the dependencies for [video/input platforms] fulfilled, the only
needed libraries should be openctm, openal, freetype, sqlite3, and lua51 or
luajit.

For openal/freetype/luajit, there is a bash script in external/git/clone.sh that
clones the repositories needed for a static build. CMake will check for the
corresponding folders during configuration, and for the ones that are found,
the normal FindModule will be side-stepped.

To set up manually, just make sure that the following git mapping is correct:

http://luajit.org/git/luajit-2.0.git external/luajit
git://git.sv.nongnu.org/freetype/freetype2.git external/freetype
git://github.com/mirros/openal-soft.git external/openal

Note that for OpenAL, only LWA will use the git mirror (in order to apply
patches) by default. For regular arcan, -DSTATIC_OPENAL=ON must also be specified.

The download script also includes 'libuvc' for portable USB based video camera
support. This is not used unless explicitly built into the decode frameserver
as a build-time option (default=Off).
