Add future imports and benchexec header with license
Add future imports and benchexec header with license

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