pub(crate) all functions prefixed with _Py

[clin1234]

No description provided.

[Icxolu]

Sorry for not mentioning this last time. What is the motivation for making them private rather than removing them? I don't see any uses of these function within pyo3-ffi and no body else could use them after this, so this would essentially become dead code.

[clin1234]

All of these functions are mentioned within https://github.com/PyO3/pyo3/blob/main/pyo3-ffi/src/impl_/macros.rs#L26-L222; do you think removing them won't cause breakage?

[Icxolu]

That is a work around for linking symbols that start with _. The corresponding arms can be removed as well, as we don't need to link these symbols anymore.