Don't cache the whole base directory; instead independently cache:
- the build output directory
- the ccache directory
This allow completely avoiding the need for building base if a
cache (keyed on the relevant parts of the git tree for base) is
successfully restored, as well as reducing the amount of cached
data.
Additionally, ensure caches are isolated by branch name (but allow
falling back to a "master" cache for restore): we don't want PRs
using each others' caches.
* junit test results; unfortunately this seems to conflict with the verbose out
* fix deps cache: two files can change independently
* verbose print obsoleted by gtest in upsream busted
* Enable parallelism in .circleci/config.yml
* Add BUSTED_SPEC_FILE to Makefile testfront
* Use it in .ci/test.sh with xargs for test parallelization
NB This is the dumb method of improving test time.
Ideally we want a workflow fan-in/fan-out approach.
