[3.15] gh-148660: Fix use-after-free in OrderedDict.copy() on reentrant mutation...

[3.15] gh-148660: Fix use-after-free in OrderedDict.copy() on reentrant mutation (GH-151573) (#152540)

gh-148660: Fix use-after-free in OrderedDict.copy() on reentrant mutation (GH-151573)

* gh-148660: Fix use-after-free in OrderedDict.copy() on reentrant mutation

OrderedDict.copy() walks the internal linked list while building the new
dict. The loop body can run arbitrary Python (a key's __eq__/__hash__, or
a subclass __getitem__/__setitem__) which can clear the source dict and
free the nodes being iterated.

Detect this the same way OrderedDict.__eq__ already does (gh-119004):
snapshot od_state before the loop, hold a strong reference to the key and
read the hash before any reentrant call, and raise RuntimeError if the
state changed before advancing to the next node.

* gh-148660: fix NEWS nit, suppress undocumented OrderedDict.copy xref
(cherry picked from commit 7d128e319f3730e776a9161a4b5e9de95c802eaf)

Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>