Create separate cgroup for main BenchExec process

[PhilippWendler]

BenchExec should put itself in a cgroup just like it does for the benchmarked process. This will be necessary for cgroup-v2 support anyway (#133), and could be used to measure the resource usage of BenchExec (and thus the benchmarking overhead).

[dbeyer]

I fully support this enhancement.

In addition to the possibility to measure BenchExec itself, this would considerably increase the security quality of BenchExec. We should keep in mind that BenchExec executes code from a wide audience of contributors on the host systems it runs on.

[dbeyer]

I fully support this enhancement.

In addition to the possibility to measure BenchExec itself, this would considerably increase the security quality of BenchExec. We should keep in mind that BenchExec executes code from a wide audience of contributors on the host systems it runs on.

My suggestion was actually about the container mode (security), which is now to be discussed in issue #384.