Check on CI whether library compiles for no_std

[tomaka]

cc #133

This PR is a revival of paritytech/smoldot#1791

It is not expected to pass CI right now, but it is a long term objective that it does.

[tomaka]

It seems that --no-default-features gets ignored when compiling from the root of the workspace. I'm pretty sure that's a cargo bug.

EDIT: actually no, it's really unclear and weird

[tomaka]

Additionally, the features of the dev-dependencies are unfortunately leaking in the --lib build.

[tomaka]

Additionally, the features of the dev-dependencies are unfortunately leaking in the --lib build.

This can be solved by building smoldot-light instead of smoldot, except for the fact that env_logger isn't no-std and that dev-dependencies can't be optional 😮‍💨

[tomaka]

Additionally, the features of the dev-dependencies are unfortunately leaking in the --lib build.

Should be solved by #656

[tomaka]

According to CI, the poly crate fails to compile for an unknown reason.
If it turns out to be a target-specific bug, I've seen people use thumbv7m-none-eabi instead.

[tomaka]

I've just pushed a commit that overwrites the version of ruzstd from crates.io to use the GitHub version instead. I've done this because I would like to see if there is any other blocker. This should obviously be reverted before merging.

[tomaka]

I'm going to merge this PR for the smoldot library, and open another one for smoldot-light.