CI failures in deserialization

…are a result of using Swift 3.2 modules in a Swift 4 context, specifically with inlinable code. I'll fix this particular issue, but I'll also use this as a reminder that @inline(__always), @_inlineable, and @_transparent are not supported for user code. We're getting away with them in the standard library purely by avoiding the known and unknown pitfalls. :-)

Jordan