feat: add all-static feature

[hack3ric]

This adds the ability to build against system libraries like libgit2 and OpenSSL, when the feature is not present.

[orhun]

The use case is https://gitlab.archlinux.org/archlinux/packaging/packages/release-plz/-/merge_requests/1

[MarcoIeni]

Thanks for the contribution! I'm happy to accept it. I'll think a bit about the name of the feature.

So on arch linux, by default the release-plz binary will use the system libraries such as git2 and openssl, right?
Is this a policy of all arch linux packages?

[MarcoIeni]

let's call this feature all-static, to follow cargo convention :)

[hack3ric]

Fixed.

[hack3ric]

So on arch linux, by default the release-plz binary will use the system libraries such as git2 and openssl, right?

After this change, yes; previously these libraries were still vendored.

Is this a policy of all arch linux packages?

Packagers generally prefer dynamic libraries for size, build speed and security reasons. I'm not an Arch Linux maintainer, but we can refer to https://www.reddit.com/r/linux/comments/9emwtu/comment/e5qssdz/ where Felix and Levente discussed about the benefits of it from a distro's perspective.

[MarcoIeni]

I see, thanks for the explanation, it makes sense :)

By default, I vendor everything so people have fewer issues when running the binary in all various systems. But package maintainers control the dependencies of the binary, so it makes sense to not vendor the other libraries.

Thanks for the contribution 🙏