[Bug libstdc++/89452] basic_stringbuf::seekoff and basic_stringbuf::seekpos implementations

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89452

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #2)
> This was changed many years ago by https://wg21.link/lwg453

... and clarified a few months ago by
https://github.com/cplusplus/draft/commit/af40423574aa8e3a495b382840a258f94cb6349d