bpo-40024: Update _elementtree to use PyModule_AddType

[corona10]

https://bugs.python.org/issue40024

[vstinner]

Would you mind to revert _decimal changes and move them into a separated PR?

[skrah]

_decimal deliberately calls PyType_Ready() at the top of PyInit__decimal(), so I don't see the need for the new function here. I'm not going to restructure the whole init.

So please just remove these changes, no need for a separate PR.

[corona10]

@vstinner @skrah
Thanks for the review :)
I 've reverted decimal. Please take a look.

[vstinner]

LGTM.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot s390x RHEL8 LTO + PGO 3.x has failed when building commit 016bdd5.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/498/builds/219) and take a look at the build logs.
4. Check if the failure is related to this commit (016bdd5) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/498/builds/219

Failed tests:

• test_concurrent_futures

Failed subtests:

• test_crash - test.test_concurrent_futures.ProcessPoolSpawnExecutorDeadlockTest
• test_crash - test.test_concurrent_futures.ProcessPoolForkserverExecutorDeadlockTest

Summary of the results of the build (if available):

== Tests result: FAILURE then FAILURE ==

404 tests OK.

10 slowest tests:

• test_concurrent_futures: 2 min 38 sec
• test_multiprocessing_spawn: 1 min 34 sec
• test_multiprocessing_forkserver: 1 min 12 sec
• test_multiprocessing_fork: 1 min 6 sec
• test_signal: 47.3 sec
• test_asyncio: 40.3 sec
• test_imaplib: 37.9 sec
• test_pydoc: 30.7 sec
• test_socket: 30.5 sec
• test_io: 30.3 sec

1 test failed:
test_concurrent_futures

15 tests skipped:
test_devpoll test_gdb test_ioctl test_kqueue test_msilib test_nis
test_ossaudiodev test_startfile test_tix test_tk test_ttk_guionly
test_winconsoleio test_winreg test_winsound test_zipfile64

1 re-run test:
test_concurrent_futures

Total duration: 6 min 52 sec

Click to see traceback logs

Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.x.edelsohn-rhel8-z.lto-pgo/build/Lib/test/test_concurrent_futures.py", line 1119, in test_crash
    executor.shutdown(wait=True)
  File "/home/dje/cpython-buildarea/3.x.edelsohn-rhel8-z.lto-pgo/build/Lib/concurrent/futures/process.py", line 712, in shutdown
    self._executor_manager_thread_wakeup.wakeup()
  File "/home/dje/cpython-buildarea/3.x.edelsohn-rhel8-z.lto-pgo/build/Lib/concurrent/futures/process.py", line 80, in wakeup
    self._writer.send_bytes(b"")
  File "/home/dje/cpython-buildarea/3.x.edelsohn-rhel8-z.lto-pgo/build/Lib/multiprocessing/connection.py", line 205, in send_bytes
    self._send_bytes(m[offset:offset + size])
  File "/home/dje/cpython-buildarea/3.x.edelsohn-rhel8-z.lto-pgo/build/Lib/multiprocessing/connection.py", line 416, in _send_bytes
    self._send(header + buf)
  File "/home/dje/cpython-buildarea/3.x.edelsohn-rhel8-z.lto-pgo/build/Lib/multiprocessing/connection.py", line 373, in _send
    n = write(self._handle, buf)
OSError: [Errno 9] Bad file descriptor