Gui: modernize C++: use equals default

src/Gui/SpinBox.cpp

@@ -57,9 +57,7 @@ ExpressionSpinBox::ExpressionSpinBox(QAbstractSpinBox* sb)
     });
 }
 
-ExpressionSpinBox::~ExpressionSpinBox()
-{
-}
+ExpressionSpinBox::~ExpressionSpinBox() = default;
 
 void ExpressionSpinBox::bind(const App::ObjectIdentifier &_path)
 {
@@ -239,10 +237,7 @@ UnsignedValidator::UnsignedValidator( uint minimum, uint maximum, QObject * pare
     t = maximum;
 }
 
-UnsignedValidator::~UnsignedValidator()
-{
-
-}
+UnsignedValidator::~UnsignedValidator() = default;
 
 QValidator::State UnsignedValidator::validate( QString & input, int & ) const
 {
@@ -458,10 +453,7 @@ IntSpinBox::IntSpinBox(QWidget* parent)
 {
 }
 
-IntSpinBox::~IntSpinBox()
-{
-
-}
+IntSpinBox::~IntSpinBox() = default;
 
 bool IntSpinBox::apply(const std::string& propName)
 {
@@ -505,10 +497,7 @@ DoubleSpinBox::DoubleSpinBox(QWidget* parent)
 {
 }
 
-DoubleSpinBox::~DoubleSpinBox()
-{
-
-}
+DoubleSpinBox::~DoubleSpinBox() = default;
 
 bool DoubleSpinBox::apply(const std::string& propName)
 {