daala: initial head-only formula

Daala is an experimental video codec. No stable releases yet,
but it's nice to have a quick way to install the current code
for testing.
Is this needed at runtime, or is it just needed to run tests? It isn't dynamically linked against.

I also don't see jpeg or libpng linked against in the daala libraries, and there aren't any executables being built - is it not installing something?