[Bug libstdc++/79743] std::experimental::optional constructor broken in gcc 6.2

[krisk0.2017.02.27 at protonmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79743

--- Comment #2 from Денис Крыськов <krisk0.2017.02.27 at protonmail dot com> ---
ok, will provided standalone .cpp next time.

Jonathan, thank you.