Remove distutils bdist_wininst command

[vstinner (Victor Stinner)]

@pf_moore

I’m happy for bdist_wininst to be removed, but FYI it looks like pycurl may still be distributing wininst installers.

The PEP 527 has been accepted, so it should no longer be accepted, but the PEP is not fully implemented yet:

• Fully implement PEP 527 · Issue #6792 · pypi/warehouse · GitHub
• Deprecate bdist_wininst - #16 by dustin