Add new macros wxDECLARE_DYNAMIC_CLASS_NO_ASSIGN_DEF_COPY() and wxDECLARE_NO_ASSIGN_DEF_COPY() and use them instead of wxDECLARE_DYNAMIC_CLASS_NO_ASSIGN() and wxDECLARE_NO_ASSIGN_CLASS() respectively to ensure that we declare a (default, if possible) copy ctor in the classes declaring an assignment operator to avoid clang warnings about not doing it.