[Bug c/82013] better error message for missing semicolon in prototype

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82013

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Andi Kleen from comment #0)
> It's especially confusing when the prototype is the last in the include
> file, because then the errors appear in another file.

Yes, that's PR c++/68615