- use gitlab pipeline DAG
- add build-check for lhcb-gcc9
- add py3 build
- restore formatting and copyright checks

Thomas Cluzel authored 4 years ago and Marco Clemencic committed 4 years ago

see https://its.cern.ch/jira/browse/LBCOMP-23



Co-authored-by: Marco Clemencic <marco.clemencic@cern.ch>

Add a new set of jobs `build-check:...` that would pass if there are no
warnings and would "fail" otherwise. Since the job is allowed to fail,
the failure would be reflected as a yellow job/pipeline status.

which means use LCG_XYpython3 instead of LCG_XY

- do not rely on LCG clang-format installation
- do not require cmake configuration