Refactor tests, add output in case of non-zero exit code.
Refactor tests, add output in case of non-zero exit code.

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