gitlab-ci: Directly use host-mapped directory for ccache
Use hardcoded /cache/mesa/ccache for the cache, so it will be shared by all jobs of all Mesa projects running on the same runner host. This should increase the hit rate and decrease the worst case storage used.
Further benefits of directly using a host-mapped directory:
- Saves up to ~1 minute per job for restoring and saving the cache contents via the GitLab CI cache mechanism
- Cache contents generated by failed jobs are no longer lost
- Jobs running in parallel on the same runner host can get hits from each other
Also enable compression, so the default maximum cache size of 5G might be sufficient.
Suggested-by: Eric Anholt eric@anholt.net
[ Including !2816 (merged) so all jobs can pass on my personal runner ]