Refactor: move wxComboBox::MSWDoPopupOrDismiss() down to wxChoice.

No real changes, just make this method available in wxChoice for the next
commit needs.

See #3113.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71103 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/combobox.h

@@ -130,7 +130,6 @@ protected:
 #if wxUSE_TOOLTIPS
     virtual void DoSetToolTip(wxToolTip *tip);
 #endif
-    void MSWDoPopupOrDismiss(bool show);
 
     // this is the implementation of GetEditHWND() which can also be used when
     // we don't have the edit control, it simply returns NULL then