[3.15] gh-148260: Use at least 1 MiB stack size on musl (GH-149993) (#150150)

[3.15] gh-148260: Use at least 1 MiB stack size on musl (GH-149993) (#150150)

gh-148260: Use at least 1 MiB stack size on musl (GH-149993)

On Linux when Python is linked to the musl C library, use a thread
stack size of at least 1 MiB instead of musl default which is 128
kiB.
(cherry picked from commit df6c157e51430e8e7458012417c534ad8c33119f)

Co-authored-by: Victor Stinner <vstinner@python.org>