[Bug c++/64181] 'noexcept' on a lambda sometimes appears to get optimised away at -O2 (or above).

[rogero at howzatt dot demon.co.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64181

--- Comment #1 from Roger Orr <rogero at howzatt dot demon.co.uk> ---
The optimization is also broken in the 5.0 head (5.0.0.20150328)