gitlab CI pipeline optimisations
We can't take advantage of the multi threading yet because current CI runners only have a single CPU thread, but it works in local testing. With better runners it could be much faster.
In the past with limited pipeline minutes, we did have problems with running out, this would help prevent that.
antilag.qc: fix indenting
this is in here because i needed some way to cause test_compilation_units to run :)
pipeline: use make jobserver to run 3 compilationunits.sh in parallel
compilationunits.sh has 3 main tasks, one for each progs.
They were run sequentially without making use of multi threading.
Also make clean now removes the temp files created by compilationunits.sh
pipeline: merge test_sv_unit into test_sv_game
The test only takes a few seconds including engine startup,
most of the time was used in preparing the environment and
compiling the same binaries as used in test_sv_game.
Also removed a bashism for robustness.