Bug 2107921

Description of problem:
The google.protobuf Python module was written with optional support for a Python extension that wraps the C++ implementation of protobuf. The serialization/deserialization performance improvements of this C++ implementation when used from Python is on the order of 12-26x according to my very unscientific tests on a development laptop when using large Protobuf messages (eg. 1M repeated values in a message). According to the protobuf git repo[1], the optional support is built using:

   python3 setup.py build --cpp_implementation

This generates some compiled shared objects (*.so) in google.protobuf.pyext and .internal. The C++ implementation is automatically selected if the binaries are present, and it falls back on the slow Python implementation if not. The desired implementation can be forced using the `PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION` environment variable (takes either `cpp` or `python`).

The python3-protobuf package on F35 and F36 is built using a simple %py3_build, meaning:

   python3 setup.py build

This means that the C++ implementation wrapper is not built, and everything runs with the slow Python-based protobuf implementation.

[1]: https://github.com/protocolbuffers/protobuf/blob/main/python/README.md#installation


Version-Release number of selected component (if applicable):
- F35: 3.14.0-6.fc35
- F36: 3.19.4-2.fc36


How reproducible:
Always


Steps to Reproduce:
1. Install python3-protobuf
2. Run `PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=cpp python3` to open Python interpreter.
3. Import a module that may use the C++ implementation: `from google.protobuf import descriptor`


Actual results:
Python throws the exception:
```
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.10/site-packages/google/protobuf/descriptor.py", line 48, in <module>
    from google.protobuf.pyext import _message
ImportError: cannot import name '_message' from 'google.protobuf.pyext' (/usr/lib/python3.10/site-packages/google/protobuf/pyext/__init__.py)
```


Expected results:
A successful import where google.protobuf wraps the C++ impementation of protobuf.


Additional info: