[3.14] gh-143196: Fix crash in non-standard use of internal JSON encoder object ...

[3.14] gh-143196: Fix crash in non-standard use of internal JSON encoder object (GH-143618) (GH-143748)

The internal encoder object returned by undocumented function
json.encoder.c_make_encoder() (aka _json.make_encoder()) crashed
when it was called with non-zero second argument.
(cherry picked from commit c559135c931789ebc752ae68814858c398cb798b)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>