Use builtin-baseline from vcpkg.json

I would suggest to support builtin-baseline (reference). It could replace vcpkgGitCommitId.

[equeim]

Yeah, second point about hashing was unrelated, I added it because I mentioned vcpkg-configuration.json and noticed that run-vcpkg doesn’t hash it by default. Sorry for the confusion.

What I meant was that baseline commit can be specified in both vcpkg.json and vcpkg-configuration.json. In the second form it would look like this object inside root object in vcpkg-configuration.json:

  "default-registry": {
    "kind": "builtin",
    "baseline": "df40d1c476dc02d71b113e4a63c3a32b00ebb5bd"
  }

So the logic that will look for commit id in vcpkg.json will also need to look in vcpkg-configuration.json. If both files have baseline commit, then vcpkg will use one provided in vcpkg-configuration.json.

[Shatur]

@lukka Exactly!