[Bug c++/83271] const variable previously declared "extern" results in "weak declaration must be public" error

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83271

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Can't we simply force it public when processing the attribute and let
duplicate-decl complain when merging a previous declaration/definition?