[patch] Use abi_tag attribute on std::list

[Marc Glisse]

On Fri, 3 Oct 2014, Jonathan Wakely wrote:

> Marc, this is the relative diff to go back to what I had earlier, with
> the size in the _List_impl in case you want to aply it locally (the
> dg-error tests are off-by-one with this patch)

Thanks. For PR 61347, to avoid offsetof, I will actually need to 
change:

- __detail::_List_node_base _M_node;
- size_t _M_size;
+ _List_node<size_t> _M_node;

and store the size in _M_node._M_data. Since I will have to touch it 
anyway, don't feel forced to move it to _M_impl.

-- 
Marc Glisse