[3.12] gh-131418: remove unused legacy typedefs in `{md5,sha1}module.c` (GH-131420...

[3.12] gh-131418: remove unused legacy typedefs in `{md5,sha1}module.c` (GH-131420) (#131619)

gh-131418: remove unused legacy typedefs in `{md5,sha1}module.c` (GH-131420)

- Remove legacy typedefs `MD5_INT32` and `MD5_INT64` in `Modules/md5module.c`
- Remove legacy typedefs `SHA1_INT32` and `SHA1_INT64` in `Modules/sha1module.c`.

Those legacy typedefs were used to detect whether the host platform could
correctly implement MD5 and SHA-1, but this is no longer needed as we now
fallback to HACL* implementations.
(cherry picked from commit a9a399f0ecfeeff91425cc089057f1b95799853b)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>