Skip cross module exception translation on FreeBSD

[cyyever]

Description

This PR skips the mentioned test on FreeBSD. Python modules are loaded with RTLD_LOCAL, which resolves the same C++ exception types into different global names. Furthermore, FreeBSD uses libc++, which unlike libstdc++, doesn't provide a specific conversion of such typeinfo differences. As a comparison, MacOS also uses libc++ but works because its modules are load with RTLD_GLOBAL (a special case handled in CPython).
The test build uses clang++19 on FreeBSD 15. But I also saw this failure on FreeBSD 14 with clang++16.

Before this PR, simply building with tests and running make check on FreeBSD outputs the error:

============================================================= FAILURES =============================================================
______________________________________________ test_cross_module_exception_translator ______________________________________________

    @pytest.mark.xfail(
        "(env.MACOS and env.PYPY) or env.ANDROID",
        raises=RuntimeError,
        reason="See Issue #2847, PR #2999, PR #4324",
        strict=not env.PYPY,  # PR 5569
    )
    def test_cross_module_exception_translator():
        with pytest.raises(KeyError):
            # translator registered in cross_module_tests
>           m.throw_should_be_translated_to_key_error()
E           RuntimeError


../../tests/test_exceptions.py:87: RuntimeError

It becomes XFAIL after this PR and all other tests also pass.

[rwgk]

Nice, thanks!

[rwgk]

@cyyever I overlooked yesterday: Could you please also report the FreeBSD version and gcc version in the PR description?

Just something very simple, e.g. on my Ubuntu workstation I'd do this:

• cat /etc/lsb-release
• g++ --version

Then copy-paste the outputs to the PR description. So that when someone looks at the PR description in the future, they easily see meaningful information about the platform.

[cyyever]

@rwgk I have added more information, BTW, I hadn't tested with gcc because clang is the default C/C++ compiler on FreeBSD.