Silenced a warning

src/storm/logic/VariableSubstitutionVisitor.cpp

@@ -50,11 +50,11 @@ namespace storm {
             return std::static_pointer_cast<Formula>(std::make_shared<BoundedUntilFormula>(left, right, lowerBound, upperBound, f.getTimeBoundType()));
         }
         
-        boost::any VariableSubstitutionVisitor::visit(CumulativeRewardFormula const& f, boost::any const& data) const {
+        boost::any VariableSubstitutionVisitor::visit(CumulativeRewardFormula const& f, boost::any const&) const {
             return std::static_pointer_cast<Formula>(std::make_shared<CumulativeRewardFormula>(storm::logic::TimeBound(f.isBoundStrict(), f.getBound().substitute(substitution)), f.getTimeBoundType()));
         }
         
-        boost::any VariableSubstitutionVisitor::visit(InstantaneousRewardFormula const& f, boost::any const& data) const {
+        boost::any VariableSubstitutionVisitor::visit(InstantaneousRewardFormula const& f, boost::any const&) const {
             return std::static_pointer_cast<Formula>(std::make_shared<InstantaneousRewardFormula>(f.getBound().substitute(substitution), f.getTimeBoundType()));
         }