Fix standard attributes in middle of decl-specifiers

[wroyca]

Attributes can only appear first in a member declaration. MSVC is lenient here, but other compilers will generate an error accordingly.

https://eel.is/c++draft/class.mem#general

[Rackover]

I'm not even sure why we have those. Somebody said it's good practice but then didn't update the whole project to use them so now they're in this tiny place and nowhere else

[wroyca]

Will make a follow-up PR to remove these. :)