swift234

[ClangImporter] Import 'NSObject <FooProto> *' as 'id <NSObject, FooProto>'.

This is usually a more helpful type than our alternative, 'NSObject', although
it's not Equatable or Hashable. Since pretty much everything from Objective-C
inherits from NSObject, though, keeping the protocol qualifiers is much more
useful from a type-safety perspective.

The particular benefit for this comes with a change to libdispatch's <os/object.h>:
with dispatch types all declaring that they inherit from NSObjectProtocol, the
canonical form of the imported 'dispatch_queue_t' is now just a simple protocol
reference. That's type-safe as above, but is also a type that can be extended.

rdar://problem/16213421

Swift SVN r30100