actor: Add IN_DESTRUCTION checks

actor: Add IN_DESTRUCTION checks

Commit 80626e75842a24c3d0a45068e241ba309f6ec138 removed an
IN_DESTRUCTION check from within the add_child_internal() method,
outlining an option for bringing it back. It was too late for the 1.10
cycle to do it, and eventually pick up the pieces, but now that we're
at the beginning of the 1.11 cycle we can restore it, and add checks
elsewhere to balance it.