Implement ccache as part of Docker builds?

[jauderho]

ccache is a compiler cache for C code. I was trying to figure out if it was possible (and useful) to use ccache across multiple GHA runs in an attempt to lower compile times for nginx etc. builds.

I was playing around with https://github.com/jauderho/dockerfiles/blob/55906f659f6f5b8e95106e8071451c5fa587a859/.github/workflows/nginx.yml but was not able to successfully come with a config that uses both actions/cache and cache-from: type=gha

If anyone wants to take a run at this, it would be much appreciated.

[jauderho]

I took another run at this after thinking more about it and think I'm part of the way there. Just need to figure out how to pass cache files in and out of the builder.

Here's the WIP: https://github.com/jauderho/sandbox/blob/main/.github/workflows/ccache.yml