fa71bedf86 ci: Approximate MAKEJOBS in image build phase (MarcoFalke)
Pull request description:
The `MAKEJOBS` env var is the default in image builds, which is fine, because it is only relevant when building msan (or iwyu) and only differs when setting MAKEJOBS to something other than `nproc` (currently used as an approximation).
So the normal workflow of `MAKEJOBS="-j$(nproc)" FILE_ENV="./ci/test/00_setup_env_native_msan.sh" ./ci/test_run_all.sh` already works today.
However, `MAKEJOBS="-j1" FILE_ENV="./ci/test/00_setup_env_native_msan.sh" ./ci/test_run_all.sh` does not.
This is hard to fix, because making the env var a build arg means that changing it (and only it) requires a new (expensive and redundant) build.
So add an option `HAVE_CGROUP_CPUSET`, which can be set to approximate `MAKEJOBS` a bit. Can be tested via:
`HAVE_CGROUP_CPUSET=yo MAKEJOBS="-j_something" FILE_ENV="./ci/test/00_setup_env_native_msan.sh" ./ci/test_run_all.sh`
ACKs for top commit:
fanquake:
ACK fa71bedf86
Tree-SHA512: 43ef194c71d726f4cfa3fe08a5894c7872150f37da7e4fa0c2d89e4572bc63acadb5dae3286a5e5cc14a8ce3e1ebcc14571f1a3541e8db2d18d2f7503764a2f3
ffe4261cb0