Use std::unordered_map<> in the GUI unit test code

This allows to use the correct types for the map keys and values too.

tests/testableframe.h

@@ -7,9 +7,10 @@
 ///////////////////////////////////////////////////////////////////////////////
 
 #include "wx/frame.h"
-#include "wx/hashmap.h"
 #include "wx/event.h"
 
+#include <unordered_map>
+
 class wxTestableFrame : public wxFrame
 {
 public:
@@ -23,7 +24,7 @@ private:
     int GetEventCount(wxEventType type);
     void ClearEventCount(wxEventType type);
 
-    wxLongToLongHashMap m_count;
+    std::unordered_map<wxEventType, int> m_count;
 };
 
 class EventCounter