go.mk: use as a plain repo instead of a submodule

[sauterp]

Description

We remove the go.mk as a submodule and ensure that it is automatically cloned and kept up to date with make.

Checklist

(For exoscale contributors)

• Changelog updated (under Unreleased block)
• Testing

Testing

If go.mk doesn't exist, it will be cloned:

❯ make build
Cloning into 'go.mk'...
remote: Enumerating objects: 308, done.
remote: Counting objects: 100% (194/194), done.
remote: Compressing objects: 100% (94/94), done.
remote: Total 308 (delta 130), reused 135 (delta 91), pack-reused 114
Receiving objects: 100% (308/308), 60.52 KiB | 911.00 KiB/s, done.
Resolving deltas: 100% (173/173), done.
mkdir -p '/home/sauterp/src/github.com/exoscale/cli/bin'
'/home/sauterp/bin/go' build \
   \
  -ldflags "-X main.commit=5890d142 -X main.branch=philippsauter/sc-88913/go-mk-provide-alternative-to-submodule-approach -X main.buildDate=2024-02-16T13:57:06+0000 -X main.version=dev " \
   \
  -o '/home/sauterp/src/github.com/exoscale/cli/bin/exo' \
  '.'

Once it exists, it will not be cloned anymore, but make ensures, that the same ref is checked out in go.mk even if it was changed before.

❯ cd go.mk
❯ git checkout HEAD^
❯ cd ..
❯ make build
mkdir -p '/home/sauterp/src/github.com/exoscale/cli/bin'
'/home/sauterp/bin/go' build \
   \
  -ldflags "-X main.commit=13af661a -X main.branch=philippsauter/sc-88913/go-mk-provide-alternative-to-submodule-approach -X main.buildDate=2024-02-16T15:23:06+0000 -X main.version=dev " \
   \
  -o '/home/sauterp/src/github.com/exoscale/cli/bin/exo' \
  '.'

[shortcut-integration]

This pull request has been linked to Shortcut Story #88913: go.mk: provide alternative to submodule approach.