No longer statically link the Swift libraries (#282)
No longer statically link the Swift libraries (#282)

`make archive` will no longer emit this message:

```
warning: Swift compiler no longer supports statically linking the Swift libraries. They're included in the OS by default starting with macOS Mojave 10.14.4 beta 3. For macOS Mojave 10.14.3 and earlier, there's an optional Swift library package that can be downloaded from "More Downloads" for Apple Developers at https://developer.apple.com/download/more/
```
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