[runtime] Push swift_getObjectType down into the runtime.
[runtime] Push swift_getObjectType down into the runtime.

It's used for class-bounded protocols, not just Foundation objects.
No test because I couldn't figure out how to write a non-compilation test.

Swift SVN r7367

apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation