CMake: Use IOptionPage convenience pattern

du -s .obj: 108344 -> 106748

Change-Id: I3c3ce0af0f0ba2e32e349d38e8a0a24feeb57485
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/cmakeprojectmanager/cmakesettingspage.h

@@ -32,8 +32,6 @@ namespace Internal {
 
 class CMakeSettingsPage : public Core::IOptionsPage
 {
-    Q_OBJECT
-
 public:
     CMakeSettingsPage();
 };