"Make libprotobuf symbols local on OSX" - fix missing

[peteboothroyd]

The initial problem is described here. The current issue is that a piper import issue has caused the fix to be removed, meaning that the problem has been reintroduced. The import issue is discussed further here. This issue is opened to track the reintroduction of the fix.

Perhaps part of the issue is that there wasn't an associated test added to verify that only a limited subset of all the available symbols were exposed in the resulting dylib. I'm not sure how/if this is possible in the current wheel building pipeline.

What version of protobuf and what language are you using?
Version: All versions as far as I know.
Language: Python

What operating system (Linux, Windows, ...) and version? macOS

What did you expect to see

The fix introduced in #8346 should be present in the setup.py file.

What did you see instead?

The fix has been removed.

[deannagarcia]

Closing the issue since the PR is merged, but feel free to open again if you still see the problem.

[alalek]

FYI, the similar problem of "all global" symbols on Linux: #3899