workflows: build: Add Meson build job

[ernestask]

This commit adds a parallel job to run Meson test builds.

[ernestask]

Seems like a misplaced -Werror is causing the Python module to not build (SWIG spits out some not-nice code).

[dgibson]

@ernestask in the github action itself I'm seeing setuptools errors before we even get to swig.

[ernestask]

Oh, right, that is caused by not having a recent-enough git. If you check the logs for the checkout step, you’ll see a warning.

[ernestask]

But this is a draft anyway, I’ll continue tinkering today.

[ernestask]

A couple of hacks later, it seems to be building.

• setuptools_scm requires a git repo, but not having git installed when using actions/checkout results in a source archive being fetched and exploded. I fixed that by adding a step before checkout to install git.

• Later, Ubuntu builds were failing as described in https://github.com/actions/checkout/issues/766, so another step was required to add $GITHUB_WORKSPACE to safe.directory in .gitconfig.

Make builds are not affected, because they use a different kludge (SETUPTOOLS_SCM_PRETEND_VERSION="0").

[dgibson]

Oh, right, that is caused by not having a recent-enough git. If you check the logs for the checkout step, you’ll see a warning.

Uh.. not recent enough which git? I'm literally working from the dtc main branch...

[ernestask]

Uh.. not recent enough which git? I'm literally working from the dtc main branch...

I mean in the Actions runner. Currently you use a base container image for multiple distros, none of which have git installed. My phrasing could have been better.

[dgibson]

Uh.. not recent enough which git? I'm literally working from the dtc main branch...

I mean in the Actions runner. Currently you use a base container image for multiple distros, none of which have git installed. My phrasing could have been better.

Ah! Now I see.

[blmaier]

A couple of hacks later, it seems to be building.

• setuptools_scm requires a git repo, but not having git installed when using actions/checkout results in a source archive being fetched and exploded. I fixed that by adding a step before checkout to install git.
• Later, Ubuntu builds were failing as described in fatal: unsafe repository (REPO is owned by someone else) in other workflow steps after running checkout actions/checkout#766, so another step was required to add $GITHUB_WORKSPACE to safe.directory in .gitconfig.

Make builds are not affected, because they use a different kludge (SETUPTOOLS_SCM_PRETEND_VERSION="0").

I opened a pull request to fix the setuptools_scm issue so a git repo is no longer required https://github.com/dgibson/dtc/pull/114

[dgibson]

@ernestask as @blmaier notes we have some fixes on the way which should make this worth rebasing.

Note that before I can apply, I'll also need at least Signed-off-by lines on each of the patches in this series. Most of the patches will also need a more substantial commit message giving the rationale for each change (just a subject line is almost never sufficient).