Simplify external build and artifact caching logic
- Transition from having a boolean and a path to just a path. The
existence of a value for the path is used in the same cases where the
boolean was checked for truth before.
- Remove IS_GLINUX in favor of IS_EXTERNAL everywhere.
- Conditionally add the cache directories to the docker volumes list and
- Make sure the cache variables and FETCH_PACKAGES are always
overridable, so that even an external build can use them.
7 files changed