CppEditor: Fix infinite loop on "find next" in include hierarchy

Change-Id: I8ee661b2d4b66704d85dd55cdd52f9e8c8d558d5
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Przemyslaw Gorszkowski <pgorszkowski@gmail.com>

src/plugins/cppeditor/cppincludehierarchy.cpp

@@ -322,6 +322,14 @@ private:
         return result;
     }
 
+    Result findStep(const QString &txt, FindFlags findFlags) override
+    {
+        m_model->setSearching(true);
+        Result result = ItemViewFind::findStep(txt, findFlags);
+        m_model->setSearching(false);
+        return result;
+    }
+
     CppIncludeHierarchyModel *m_model; // Not owned.
 };