[Bug c++/70667] SFINAE error disambiguating using alignas

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70667

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
If we had:
```
int i = f<3>(nullptr);
```
clang, edg and MSVC also rejects it for the same reason as GCC.