[v3] minor simplification to std::list

[Jonathan Wakely]

On 18 March 2012 23:27, Jonathan Wakely wrote:
> Now that G++ supports it we can use a NSDMI for std::list::_M_size to
> avoid needing conditional compilation to set it in the constructors.
> I think the attached patch is an improvement so I plan to commit it to
> trunk soon unless I hear objections.
>
>        * include/bits/stl_list.h (list::_M_size): Use NSDMI.
>        * testsuite/23_containers/list/requirements/dr438/assign_neg.cc:
>        Adjust line numbers.
>        * testsuite/23_containers/list/requirements/dr438/
>        constructor_1_neg.cc: Likewise.
>        * testsuite/23_containers/list/requirements/dr438/
>        constructor_2_neg.cc: Likewise.
>        * testsuite/23_containers/list/requirements/dr438/insert_neg.cc:
>        Likewise.
>
> Tested x86_64.

Committed to trunk.