swift234

[Swift runtime] Deallocation of partial class instances for Objective-C-derived classes.

Teach swift_deallocPartialClassInstance how to deal with classes that
have pure Objective-C classes in their hierarchy. In such cases, we
need to make sure a few things happen:

1) We deallocate via objc_release rather than
swift_deallocClassInstance.
2) We only attempt to find an execute ivar destroyers for
Swift-defined classes in the hierarchy
3) When we hit the most-derived pure Objective-C class, make sure that we
only execute the dealloc of that class and not any of the subclasses
(which would end up trying to destroy ivars again).

Fixes rdar://problem/25023544.