LLVM's APT repo is back on track and up-to-date with trunk --> CircleCI is green again!

I hope we can keep it green by updating AppVeyor's LLVM package whenever LLVM trunk has an API breaking change. I.e. whenever CircleCI starts to fail compilation because of an LLVM change: update AppVeyor's package and fix the LLVM3.9 compile. I'm often available to start a new AppVeyor package build, so ping me if it is needed.

cheers,
  Johan