Added build target osx-lib to build an OSX static library.

[fdeantoni]

To make development with Zenroom on OSX easier, I created a build target to create a static library for OSX. I'm not familiar with all clang build parameters, but so far the generated static library seems to work well in other projects (C, Rust).

[puria]

Thank you so much @fdeantoni. You would also add the target to the docs https://github.com/DECODEproject/Zenroom/blob/master/docs/pages/how-to-build.md with a brief explaination? 🙏

[fdeantoni]

Hi @puria, I can do that, but is seems to section on "static builds" is out of date as it mentions targets such as bootstrap, static, and check-static which I think dont exist anymore?

[puria]

thanks @fdeantoni just added a separate issue to update the static targets as soon as we can (or if you also want to take care ;p). In the meantime you can go with the osx-lib, so I'll merge this PR.

[puria]

@fdeantoni do you also have a concrete usage example? So we can put a super quick small test fixture (to run on the CI).

[fdeantoni]

Hi @puria, the example I have is a small project to create Rust bindings for Zenroom, see here: zenroom.rs. Not sure if this is what you were looking for though. I created the osx-lib build target to make development of this library slightly easier (as I develop on OSX).

[puria]

Enough then ;)

[andrea-dintino]

@fdeantoni thanks for the contribution! We have a channel about Zenroom on Telegram, you're most welcome to join: https://t.me/zenroom