[Bug libstdc++/78420] [6/7 Regression] std::less is not a total order with -O2 enabled

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78420
Bug 78420 depends on bug 85040, which changed state.

Bug 85040 Summary: [8 Regression] std::less<void> fails when operator< is 
overloaded
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85040

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