[new port] Native standalone version of gn build system

[Kurt Jaeger]

Hi!

> Gn, chromium build system, now is standalone project. FreeBSD support was added to source tree recently.
> 
> I propose create a new port devel/gn. I created PR with patch - https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=234309.
> 
> Can anyone look on it?

Committed, thanks!

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pi at opsec.eu            +49 171 3101372                    One year to go !