pythonPackages.setuptools: Remove windows files and make reproducible

- setuptools includes *.exe files by default, but can be excluded with an ENV variable.
- setuptools was built as an egg, which had reproducibility problems. Instead use a wheel

These are various *.exe and *.xml files used only on windows. setuptools
includes them by default since it normally creates a single release for
all operating systems.

This reduces the size from 1020.0K to 801.6K according to `nix-path -sh`.

The egg is a zip file. setuptools leaves timestamps in the egg,
which makes the build unreproducible. Unfortunately the files aren't
compressed so the size of setuptools increases to 2.3M from 0.8M
according to `nix path-info -sh`.

With this change, setuptools is reproducible according to

    nix-build -A python37Packages.setuptools --check