[Bug libstdc++/86169] .data() fails to unshare strings

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86169

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Oh dear, this should have removed the 'noexcept' from the non-const data(),
since it might now fail to allocate.