swift234

Allow a Swift and a Clang module to have the same name, and load both.

This change allows client code to just use, e.g.,

  import Foundation

to get both the Clang Foundation module and the Swift Foundation
module that provides various adaptation (typically via
extensions). At some point later, we can consider whether the modules
will end up in different namespaces somehow, or whether this is best
tackled by some kind of module re-export directive, but for now it's
convenient while we await the design of a real module system for
Swift.



Swift SVN r3405