net/ndproxy: Update 3.2 => 3.3, fix build on 15+

Commit log:
https://github.com/AlexandreFenyo/ndproxy/compare/v3.2...v3.3

Improve port:

• Add patch with fix build on 15+.
• Replace PORTVERSION with DISTVERSION.
• Add option DOCS.
• Fix warnings from portclippy.

PR: 291782
Approved by: Alexandre Fenyo <fbsd.bugzilla@fenyo.net> (maintainer, implicit - inactive since 2019)
Co-authored-by: David Hauweele <david@hauweele.net>