...when the optional object type is a class or Objective-C protocol type.
This is currently hidden behind -enable-objc-optional because I didn't test
if the generated code is actually correct.
Also add PrintAsObjC support for these.
Known missing pieces: blocks, and Swift structs bridged to Objective-C classes
(right now, just String).
Swift SVN r14416
This is using the compatibility macro SWIFT_CLASS, so older Clangs can still
parse a generated header on its own. This will only be interesting in a
mixed-source target, where we may need to merge a forward declaration with
a Swift-generated @interface. (See <rdar://problem/16076729>.)
Swift SVN r14411
This is a bit ironic considering we're importing NSUInteger as Int rather
than UInt, but Swift should never be using the headers it prints anyway.
Swift SVN r14088
