[3.13] gh-125698: Autoconf: Sync EXEEXT and ac_exeext (GH-125995) (#126006)

(cherry picked from commit 8b7cdc5e0c3ee9903d41a2bfc494148db32dc379)

Co-authored-by: Erlend E. Aasland <erlend@python.org>
2 files changed