refactor(contractor/contractor_ibex_fwdbwd): Use make_unique
refactor(contractor/contractor_ibex_fwdbwd): Use make_unique

soonho-tri/dreal4,soonho-tri/dreal4,dreal/dreal4,soonho-tri/dreal4,dreal/dreal4,dreal/dreal4,dreal/dreal4,soonho-tri/dreal4