Summary:
When using `setuptools` to build a Python extension, setuptools will automatically add an ABI suffix like `cpython-37m-x86_64-linux-gnu` to the shared library name when using Python 3. This is required for extensions meant to be imported as Python modules. When we use setuptools to build shared libraries not meant as Python modules, for example libraries that define and register TorchScript custom ops, having your library called `my_ops.cpython-37m-x86_64-linux-gnu.so` is a bit annoying compared to just `my_ops.so`, especially since you have to reference the library name when loading it with `torch.ops.load_library` in Python.

This PR fixes this by adding a `with_options` class method to the `torch.utils.cpp_extension.BuildExtension` which allows configuring the `BuildExtension`. In this case, the first option we add is `no_python_abi_suffix`, which we then use in `get_ext_filename` (override from `setuptools.build_ext`) to throw away the ABI suffix.

I've added a test `setup.py` in a `no_python_abi_suffix_test` folder.

Fixes https://github.com/pytorch/pytorch/issues/14188

t-vi fmassa soumith
Pull Request resolved: https://github.com/pytorch/pytorch/pull/14130

Differential Revision: D13216575

Pulled By: goldsborough

fbshipit-source-id: 67dc345c1278a1a4ee4ca907d848bc1fb4956cfa