bug#50493: Update go-build-system to use Go 1.17.

[Sarah Morgensen]

Hello Guix,

This is intended to be a tracking issue for updating go-build-system to
use Go 1.17 by default.  The build system currently uses Go 1.14, which
no longer receives security updates [0].

Here's what needs to be done:

1. Address the aarch64 bug [1], either by verifying that it only happens
on emulated systems, or by fixing it if not.

2. Make some much-needed improvements to go-build-system [2]:

* replace the *slow* phase 'remove-go-references with -trimpath option

* avoid building a directory union of Go inputs (and then copying it!)

* add a "go-std-cache-for-build" package (hidden; name to be
bikeshedded), which will be an implicit input in go-build-system (needed
since we removed the pre-built standard library in go-1.17)

3. Some/all Docker packages still require Go 1.14; make them use go-1.14
explicitly.  Alternatively, update Docker (significant effort involved).

4. Update or patch broken packages.  I've got patches for four so far:

go-github-com-urfave-cli
go-github-com-urfave-cli-v2
go-github-com-sevlyar-go-daemon
go-github-com-keybase-go-ps

I'll submit them as a separate patch and block this with it.  If anyone
else would like to see if their favorite package works with Go 1.17, you
can build it with:

  go build --with-input=go@1.14=go@1.17 <package>

[0] https://github.com/golang/go/wiki/Go-Release-Cycle#release-maintenance
[1] https://issues.guix.gnu.org/49921
[2] https://issues.guix.gnu.org/50227#10

--
Sarah