swift234

Turn on namespacing of Objective-C class names.

The actual logic to do this is simple; the vast majority of this
commit is just a pile of changes to test cases to reflect the fact
that Objective-C metadata now includes the module name for each class
and the mangling of Swift-defined @objc classes no longer goes into
the "So" namespace for Objective-C classes. Finishes
<rdar://problem/15506580>.


Swift SVN r16274