Make mkExtension put headers in the dev output and use them, instead of a different part of the current source tree, when referring to another extension by using internalDeps. This means external extensions can be built against the internal ones.
Make mkExtension put headers in the dev output and use them, instead of a different part of the current source tree, when referring to another extension by using internalDeps. This means external extensions can be built against the internal ones.