Co-authored-by: Jens Vagelpohl <jens@plyp.com>

Python 3.11 warns:

  DeprecationWarning: It is deprecated to return a value that is not
  None from a test case (<bound method Test_c3_ro.test_complex_diamond
  of <zope.interface.tests.test_ro.Test_c3_ro
  testMethod=test_complex_diamond>>)

Rearrange slightly to avoid this.

Add a regression test for CFLAGS not having -Ofast, which is known to
break things.  See https://github.com/zopefoundation/meta/pull/155 for
reference.

This reverts commit dc2e4b9841185889bdf8b77ee5c28f5b7295578a, which
itself was reverting commit 22a761cc9e6fcfa840582d55a15abda31a9dd2e1,
which was accidentally pushed to git master and is otherwise identical
to this commit.

This reverts commit 22a761cc9e6fcfa840582d55a15abda31a9dd2e1.

This was not supposed to have been pushed directly to master :/

Add a regression test for CFLAGS not having -Ofast, which is known to
break things.  See https://github.com/zopefoundation/meta/pull/155 for
reference.

On PyPy3 the following `registered_classes` for `IMutableMapping` are
found:

```
{<class 'dict'>,
 <class 'pkg_resources._vendor.pyparsing.ParseResults'>,
 <class 'setuptools._vendor.pyparsing.ParseResults'>,
 <class 'collections.UserDict'>}
```

So collecting the tests fails because of a duplicate name which is
prevented by this commit.

Co-authored-by: Michael Howitz <mh@gocept.com>

* Fix tests on Python 3.10.
* "Fix" a test broken just on windows + allow to use posargs for tox test runs.
* Checking array.array non-strictly did not help on Windows. – So ignore it completely.

`ComponentLookupError`, `Invalid`, `Registered`, and `Unregistered` are
all documented
(https://zopeinterface.readthedocs.io/en/latest/api/components.html), so
it seems odd not to list them in `__all__`.  `ObjectEvent` isn't
documented there, but it seems reasonable to export it as a base class
for similar events.

* Add support for Python 3.9.
* Improve coverage.