Add CoreFoundation framework

[silvanshade]

I thought I would give CoreFramework a try finally since so many of the remaining frameworks rely on it one way or another.

I opted to add the libc crate as a dependency to define some of the things needed. This may be relevant for #305.

[samuelsleight]

What's the current status of this branch/pull request? I'm looking into adding support for the AVFoundation framework, which I think makes sense to base off this work to add CoreFoundation given it looks like it pulls in a lot of other frameworks that all also depend on this.

I do have a (currently unpushed) branch with the conflicts resolved on this that I'd made some progress on, and I'm happy to look into tidying that up at some point, if this current PR is essentially dead?

[madsmtm]

I think it's gone somewhat stale, since I intend to replace the header-translator in a few months, and as such don't have much motivation to work on it currently.

But if you manage to get something working, that probably won't stop me from merging it in the interim.

[samuelsleight]

Fair enough, I'll see where I get to with that then!

I'll likely also submit a PR for at least one other framework beforehand, as there's at least one that doesn't appear to depend on this or indeed anything else