[PATCH] tools: add libyaml

[Petr Štetiar]

Paul Spooren <mail at aparcar.org> [2020-07-29 12:45:25]:

> Once available this can be used within a CI to reduce human resources
> spent on reviewing DTS files.

That's indeed cool, but I quite fail to see why this needs to be in the tree
right now. I would understand this patch as part of a bigger patch series
which would add somehow minimal/proof-of-concept yet complete YAML/DTS
validation support to the tree.

So in the end, both CI bot and developer on local machine could run same
commands, like `make validate-dts target/linux/foo/dts/bar.dts` etc.

Meanwhile I would simply add all the missing bits into separate Docker image
tailored specifically for DTS validation on CI. Or we could even add those
bits into the `openwrt-ci/native-testing` container image.

-- ynezz