Fix support for partial autogen.
Partial autogen means that some lifecycle functions are possible to generate, and needed, while others are impossible to generate, but unneeded. It is a valid situation that a user can implicitly request.
Previous handling of "impossible to generate" left the function in a zombie state, where it could show up as an alternative later. This zombie state is problematic handling caused by a compiler bug. Without the fix, the added test fails by creating zombie states.
This change is also a prerequsite for an upcoming change to avoid gcc warnings by not emitting autogen forward declarations.
