CppTools: Use override consistently

clang-tidy fixes from modernize-use-override check.

Change-Id: I0e6d6a9df3e87b8042ccc5ea0adc70070a3821d6
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/plugins/cpptools/cppsemanticinfoupdater.h

@@ -40,7 +40,7 @@ class SemanticInfoUpdater : public QObject
 
 public:
     explicit SemanticInfoUpdater();
-    ~SemanticInfoUpdater();
+    ~SemanticInfoUpdater() override;
 
     SemanticInfo semanticInfo() const;