Intent to remove: Go 1.9, 1.10, 1.16 (?), 1.17

[Benny Siegert <bsiegert%gmail.com@localhost>]

Hi!

We have quite the proliferation of different Go versions in pkgsrc:

go-bin (binary bootstrap kit used notably on aarch64)
1.4 (used for bootstrapping since it is still written in C)
1.9 (for NetBSD 6)
1.10 (for macOS 10.8 and 10.9)
1.16 (gdt@ said that syncthing broke with newer versions)
1.17 (now end of life)
1.18
1.19

I would like to remove 1.9 and 1.10 because they simply are not useful
anymore. They can only build code in GOPATH mode, whereas practically
all Go projects these days use modules, which were introduced in 1.11.

I would also like to remove 1.17 because it is end of life.

As for 1.16: Greg, would you like to keep it around for the time being?

Unless there are objections, I would like to remove these versions
after the next branch.

-- 
Benny