Add tests for statistics computation.
Add tests for statistics computation.

martin-neuhaeusser/benchexec,sosy-lab/benchexec,dbeyer/benchexec,IljaZakharov/benchexec,sosy-lab/benchexec,sosy-lab/benchexec,dbeyer/benchexec,martin-neuhaeusser/benchexec,ultimate-pa/benchexec,ultimate-pa/benchexec,ultimate-pa/benchexec,sosy-lab/benchexec,martin-neuhaeusser/benchexec,ultimate-pa/benchexec,IljaZakharov/benchexec,ultimate-pa/benchexec,IljaZakharov/benchexec,sosy-lab/benchexec,ultimate-pa/benchexec,sosy-lab/benchexec,dbeyer/benchexec,martin-neuhaeusser/benchexec,michkot/benchexec,dbeyer/benchexec,IljaZakharov/benchexec,michkot/benchexec,michkot/benchexec