This patch hooks up the swiftCore library build and gets it installing.
This means that we have library evolution hooked up and vector types.
Building it dynamically found that we had duplicate symbols, so fixed
the swiftDemanglingCR library.
Needed to hook up the availability macros.
The flag configuration is for macOS, so we'll need to go through and
figure out what it should look like for the other platforms too.
Adding stdlib stubs library, which uses gyb and requires knowing about
some of the platform info.
The stubs library pulls in several headers from the compiler repository.
We should probably clean that up, but not right now. I've made a note of
it.
Adding a readme describing the different layers for the standard
libraries, and what libraries belong to which layer.
- Core: The core runtime libraries that provide basic operations
- Overlay: Maps the underlying system into Swift
- Supplemental: Libraries that use the underlying system
- Testing: Extraneous support for testing the standard libraries
