swift234

Partially applying a throwing function requires a thunk, even
if the only partially-applied argument is a Swift-refcountable
pointer.  However, it doesn't require a new heap allocation,
so teach partial-application forwarding how to emit a thunk
when the only capture is directly usable as the context.

Fixes rdar://21084084.

or at least as long as we don't emit the throwing function

Swift SVN r29131