Put private wxQtChoice class inside an anonymous namespace

No real changes, just avoid polluting global scope unnecessarily.

src/qt/choice.cpp

@@ -12,6 +12,9 @@
 #include "wx/qt/private/winevent.h"
 #include <QtWidgets/QComboBox>
 
+namespace
+{
+
 class wxQtChoice : public wxQtEventSignalHandler< QComboBox, wxChoice >
 {
 public:
@@ -36,6 +39,8 @@ void wxQtChoice::activated(int WXUNUSED(index))
         handler->SendSelectionChangedEvent(wxEVT_CHOICE);
 }
 
+} // anonymous namespace
+
 
 wxChoice::wxChoice() :
     m_qtComboBox(NULL)