We can optionally use this setup for our full dependency tree, but I'm not 100%
sure that's the best idea yet, but it does seem better than having it in a
separate repository.

I made sure I had libnice-dev installed on debian and configured and built with with build-dependencies set to true and false.
I think removed libnice-dev and verified meson failed to configure with build-dependencies=false. I then reconfigured to set build-dependencies=true and verified that meson said it was going to build the subproject, and then I built the entire repository.