I have obtained the sources via git from GitHub - nginx/nginx: An official read-only mirror of http://hg.nginx.org/nginx/ which is updated hourly. Pull requests on GitHub cannot be accepted and will be automatically closed. The proper way to submit changes to nginx is via the nginx development mailing list, see http://nginx.org/en/docs/contributing_changes.html
but seem to be missing a ‘configure’ script.
Where/how do I get that?