Fix UnbindFromHandler() test compilation with C++98

Can't declare classes inside the function as they must have external linkage
to be usable with Bind().

Fixes the build after 99d9a81e28, see #17229.

tests/events/evthandler.cpp

@@ -462,8 +462,8 @@ void EvtHandlerTestCase::InvalidBind()
 #endif
 }
 
-void EvtHandlerTestCase::UnbindFromHandler()
+// Helpers for UnbindFromHandler() test, have to be declared outside of the
-{
+// function in C++98.
 struct Handler1
 {
     void OnDontCall(MyEvent&)
@@ -473,35 +473,38 @@ void EvtHandlerTestCase::UnbindFromHandler()
         // before it has a chance to be called.
         CPPUNIT_FAIL("shouldn't be called");
     }
-    } h1;
+};
-
-    handler.Bind(MyEventType, &Handler1::OnDontCall, &h1);
 
 class Handler2
 {
 public:
     Handler2(MyHandler& handler, Handler1& h1)
+        : m_handler(handler),
+          m_h1(h1)
     {
-            m_handler = &handler;
-            m_h1 = &h1;
     }
 
     void OnUnbind(MyEvent& e)
     {
-            m_handler->Unbind(MyEventType, &Handler1::OnDontCall, m_h1);
+        m_handler.Unbind(MyEventType, &Handler1::OnDontCall, &m_h1);
 
         // Check that the now disconnected first handler is not executed.
         e.Skip();
     }
 
 private:
-        // Use pointers instead of references just to avoid warnings about the
+    MyHandler& m_handler;
-        // class being non-copyable even though these pointers don't change and
+    Handler1& m_h1;
-        // are non-NULL.
-        MyHandler* m_handler;
-        Handler1* m_h1;
-    } h2(handler, h1);
 
+    wxDECLARE_NO_COPY_CLASS(Handler2);
+};
+
+void EvtHandlerTestCase::UnbindFromHandler()
+{
+    Handler1 h1;
+    handler.Bind(MyEventType, &Handler1::OnDontCall, &h1);
+
+    Handler2 h2(handler, h1);
     handler.Bind(MyEventType, &Handler2::OnUnbind, &h2);
 
     handler.ProcessEvent(e);