removed duplicated prototype

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@12471 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/motif/msgdlg.h

@@ -51,12 +51,5 @@ protected:
     long        m_result;
 };
 
-
-int WXDLLEXPORT wxMessageBox(const wxString& message,
-                             const wxString& caption = wxMessageBoxCaptionStr,
-                             long style = wxOK | wxCENTRE,
-                             wxWindow *parent = NULL,
-                             int x = -1, int y = -1);
-
 #endif
     // _WX_MSGBOXDLG_H_