CppEditor: Add missing include

Change-Id: I5a8724987e3c5888d5d07507cf2ae63a1b463c5a
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/cppeditor/cppoverviewmodel.cpp

@@ -34,6 +34,8 @@
 #include <utils/linecolumn.h>
 #include <utils/link.h>
 
+#include <QTimer>
+
 using namespace CPlusPlus;
 namespace CppEditor::Internal {