[Bug c++/116911] [15 regression] reference to a variable in anonymous namespace no longer considered constexpr in C++11

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116911

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note we should accept this for C++11 too:
```
template <int &> struct a {};
static int guard;
a<guard> b;
```

But that has always been rejected.
clang warns about the original reduced testcase for c++98 but that is valid as
anonymous namespaces are not local linkage in C++98 (even though they are
localized).