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

[emi_cuenca at hotmail dot com]

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

--- Comment #2 from emi_cuenca at hotmail dot com ---
Created attachment 41782
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41782&action=edit
Proposed patch