[Bug libstdc++/88322] Implement C++20 library features.

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88322
Bug 88322 depends on bug 103934, which changed state.

Bug 103934 Summary: std::atomic_flag: multiple C++20 functions missing
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103934

           What    |Removed                     |Added
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             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED