Pyoxidizer build fails on fabric dependency (mac)

When I include fabric in my dependencies (regardless of how I add the resource) I get:

```
error: adding PythonExtensionModule

Caused by:
extension module _cffi_backend cannot be loaded from memory but memory loading required
```

I've tried to get resources using setup.py, using an exiting virtualenv, and using `exe.add_python_resources(exe.pip_install([...]))` with an explicit list of packages. All methods result in the same error and at the very least it is cause by fabric, presumably because of the SSH dependency.

Reproduce the macOS build with fabric included, using the listed setup.py, existing virtualenv, and exe.pip_install approaches. Start by tracing how the _cffi_backend PythonExtensionModule is loaded from the installed resources; done means a fabric dependency can be packaged without the memory-loading error.

Written by the indexing model from the issue text.