updated determine_result
updated determine_result

the modified code avoids using generic terms like "failed" for tool's output
martin-neuhaeusser/benchexec,ultimate-pa/benchexec,IljaZakharov/benchexec,sosy-lab/benchexec,dbeyer/benchexec,sosy-lab/benchexec,IljaZakharov/benchexec,dbeyer/benchexec,ultimate-pa/benchexec,sosy-lab/benchexec,IljaZakharov/benchexec,sosy-lab/benchexec,ultimate-pa/benchexec,sosy-lab/benchexec,dbeyer/benchexec,ultimate-pa/benchexec,sosy-lab/benchexec,dbeyer/benchexec,martin-neuhaeusser/benchexec,ultimate-pa/benchexec,IljaZakharov/benchexec,ultimate-pa/benchexec,martin-neuhaeusser/benchexec,martin-neuhaeusser/benchexec