[Bug c++/88323] implement C++20 language features.

[emsr at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88323
Bug 88323 depends on bug 88336, which changed state.

Bug 88336 Summary: Implement P0595R2, C++20 std::is_constant_evaluated 
(compiler magic library tool).
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88336

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