[Bug libstdc++/110339] Implement C++26 library features

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110339
Bug 110339 depends on bug 113310, which changed state.

Bug 113310 Summary: [C++26] Implement P2819R2 Add tuple protocol to complex
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113310

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