python / cpython

…eed (GH-16630)

Some objects like Py_None are not initialized with conventional means
that prepare the circular linked list pointers, leaving them unlinked
from the rest of the objects. For those objects, NULL pointers does
not mean that they are freed, so we need to skip the check in those
cases.
(cherry picked from commit 36e33c3)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>