Move the calculation which cores should be assigned to the current run
out of the setupCGroups method of runexecutor.py.
This calculation should be done at the beginning of the benchmark
with global knowledge.
Furthermore, this is the main remaining difference of this script
to its VerifierCloud version.

git-svn-id: https://svn.sosy-lab.org/software/cpachecker/trunk@14810 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c