Remove duplicate declaration of shared_ptr_node_size

include/foonathan/memory/smart_ptr.hpp

@@ -191,18 +191,6 @@ namespace foonathan
                                                detail::forward<RawAllocator>(alloc)),
                                            detail::forward<Args>(args)...);
         }
-
-#if !defined(DOXYGEN)
-#include "detail/container_node_sizes.hpp"
-#else
-        /// Contains the node size needed for a `std::shared_ptr`.
-        /// These classes are auto-generated and only available if the tools are build and without cross-compiling.
-        /// \ingroup adapter
-        template <typename T>
-        struct shared_ptr_node_size : std::integral_constant<std::size_t, implementation_defined>
-        {
-        };
-#endif
     } // namespace memory
 } // namespace foonathan