[Bug libstdc++/58403] __normal_iterator triggers odr-use

[lichray at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58403

--- Comment #9 from Zhihao Yuan <lichray at gmail dot com> ---
(In reply to Jonathan Wakely from comment #7)
> [...] It is unspecified whether
> "it += A::a" is an odr-use or not.

Well, it's true, but I guess the primary purpose of making
containers' iterator implementation-defined is to allow
raw pointers instead of to make it harder to use...

I think we have the consensus that this is OK to change,
though.