trying to share/publish a constant value fails

[UnixJunkie]

this is kind of a stupid use case, but since users are not preventing from doing it by the type system...
Not sure it can be supported though.

[UnixJunkie]

maybe Is_in_heap_or_young should be replaced by Is_in_value_area from
https://github.com/ocaml/ocaml/blob/d3e73595e55e84250fa77f04e9c239dee1224b7b/runtime/caml/address_class.h
Not sure it is safe to do so, though.

[UnixJunkie]

e.g.

let _ = Ancient.share shm key 12345 in

[UnixJunkie]

@rwmjones