Iterating child tasks depends on knowing the size of AsyncTask, and changing the size of the task broke it. Instead of relying on mirroring the full structure in our out-of-process definitions, add a debug variable to libswift_Concurrency that contains the size of AsyncTask.
While we're there, add some more validation to child task enumeration. Check each child task's metadata pointer to make sure that it actually points to the AsyncTask metadata, and have the inner loop also increment and check ChildTaskLoopCount to stop runaway iteration in that loop.
rdar://148836760
(cherry picked from commit e3057031da)
The definition of `DefautlActorImpl` changed in https://github.com/swiftlang/swift/pull/73998. This change reflects those changes on to RemoteInspection's platform independent definition.
