Use config file instead of environment to configure ccache

[dschuff]

Using a file will make it easier to set configurations from an earlier step to a later one, or to use a different configuration for the main and other branches.

Also dump some additional log info after building.

[sbc100]

You could just do stuff like echo "debug = true\n" >> ~/.ccache/ccache.conf instead of checking in a new file, right?

[dschuff]

Yes. I figured if we have several lines it would be better to have a file than a bunch of echos though?

[dschuff]

Or a heredoc style echo could be good, but I didn't know if that would compose well with YAML.

[dschuff]

Going to land this for now to keep experimenting, I can switch it later if we want to keep a persistent config.

[sbc100]

Going to land this for now to keep experimenting, I can switch it later if we want to keep a persistent config.

echo SOMETHING >> file is actually pretty common in github actions yaml script IIRC (its how to persist bach env vars I think).