Ideally, we want to make CircleCI a "fast" test environment, with short feedback loop (~5mn).
We are still far from this goal.
This patch starts this process by removing "long" tasks which are non-essential and redundant with travisCI.
It also acknowledges that parallelism is broken.
The script should be more heavily updated to support parallelism,
which might be important to support its goal.
- only play listTest with `make test`, not `make all` which is limited to build
- update `clangtest`, so that it's possible to disable O3 optimization, for faster processing
