[Bug libstdc++/114553] Undefined symbol in directory_iterator move assignment operator with -Os

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114553

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Just FYI. this is the uninclude example:
```
#include "filesystem"
namespace fs = std::filesystem;

int main() {
  auto iter = fs::directory_iterator();
  iter = fs::directory_iterator();
}

```

Because this is a libstdc++ issue with the shared library and not exporting the
"right thing" as -static-libstdc++ works.