[Patch, libstdc++/64239] Fix regex_iterator copying

[Jonathan Wakely]

On 11/12/14 00:27 -0800, Tim Shen wrote:
>As discussed in Bugzilla.
>
>Bootstrapped and tested.

OK for trunk.

>Is it Ok to backport it to 4.9 branch, with _M_in_iterator kept unused?

Yes, that's OK as well.

Thanks.