Define functions as deleted

Change-Id: I8227c439a9d74283d108514cdd349b9e534342f7
diff --git a/include/vcl/button.hxx b/include/vcl/button.hxx
index a020bd6..1bd740c 100644
--- a/include/vcl/button.hxx
+++ b/include/vcl/button.hxx
@@ -133,9 +133,9 @@ protected:
    SAL_DLLPRIVATE bool            IsSymbol() const { return ( (meSymbol != SymbolType::DONTKNOW) && (meSymbol != SymbolType::IMAGE) ); }
    SAL_DLLPRIVATE bool            IsImage() const { return Button::HasImage(); }

    // Copy assignment is forbidden and not implemented.
    SAL_DLLPRIVATE                 PushButton( const PushButton & );
    SAL_DLLPRIVATE                 PushButton& operator=( const PushButton & );
                                   PushButton( const PushButton & ) = delete;
                                   PushButton& operator=( const PushButton & )
                                       = delete;

    SAL_DLLPRIVATE void            ImplInit( vcl::Window* pParent, WinBits nStyle );