Make wxQtSpinBoxBase-derived valueChanged() methods inline

It seems better to have them in the class itself, near the connect()
call binding them.

This also resolves an inconsistency between wxQtSpinBox::valueChanged(),
which was defined elsewhere in the source file, and the same method of
wxQtDoubleSpinBox, which was defined directly after the class
declaration.

See https://github.com/wxWidgets/wxWidgets/pull/1168

src/qt/spinctrl.cpp

@@ -154,7 +154,16 @@ public:
                 this, &wxQtSpinBox::valueChanged);
     }
 private:
-    void valueChanged(int value);
+    void valueChanged(int value)
+    {
+        wxControl *handler = GetHandler();
+        if ( handler )
+        {
+            wxSpinEvent event( wxEVT_SPINCTRL, handler->GetId() );
+            event.SetInt( value );
+            EmitEvent( event );
+        }
+    }
 };
 
 class wxQtDoubleSpinBox : public wxQtSpinBoxBase< QDoubleSpinBox >
@@ -167,10 +176,7 @@ public:
                 this, &wxQtDoubleSpinBox::valueChanged);
     }
 private:
-    void valueChanged(double value);
-};
-
-void wxQtDoubleSpinBox::valueChanged(double value)
+    void valueChanged(double value)
     {
         wxControl *handler = GetHandler();
         if ( handler )
@@ -180,6 +186,7 @@ void wxQtDoubleSpinBox::valueChanged(double value)
             EmitEvent( event );
         }
     }
+};
 
 
 //##############################################################################
@@ -236,17 +243,6 @@ void wxSpinCtrl::SetValue( const wxString &value )
         qtSpinBox->setValue( qtSpinBox->valueFromText( wxQtConvertString( value )));
 }
 
-void wxQtSpinBox::valueChanged(int value)
-{
-    wxControl *handler = GetHandler();
-    if ( handler )
-    {
-        wxSpinEvent event( wxEVT_SPINCTRL, handler->GetId() );
-        event.SetInt( value );
-        EmitEvent( event );
-    }
-}
-
 //##############################################################################
 
 template class wxSpinCtrlQt< double, QDoubleSpinBox >;