[Bug libstdc++/81469] std::uncaught_exception should be marked as deprecated for C++1z

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81469

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Patches should be sent to the gcc-patches anbd libstdc++ mailing lists, not
attached to bugzilla.

The line should be wrapped to less than 80 columns, and C++1z should be C++17,
although I wouldn't bother with "in C++1z" at all.