CppTools: Use unshared object for CppCodeModelSettings

There's nothing shared here, only ever one copy. Ideally, this
should be const outside CppToolsPlugin, but some settings
are modified directly.

Change-Id: I775b9151a244b3cc44d28bc992a041c42d234a18
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/cpptools/cppcodemodelsettingspage.h

@@ -35,7 +35,7 @@ namespace Internal {
 class CppCodeModelSettingsPage final : public Core::IOptionsPage
 {
 public:
-    explicit CppCodeModelSettingsPage(QSharedPointer<CppCodeModelSettings> &settings);
+    explicit CppCodeModelSettingsPage(CppCodeModelSettings *settings);
 };
 
 } // Internal namespace