Do not crash if output directory already exists.
Do not crash if output directory already exists.

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