[clang] [C23] Implement N3018: The constexpr specifier for object definitions (PR #73099)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

Thank you for working on this! First round of comments done (I've not thoroughly reviewed the test cases yet though).

https://github.com/llvm/llvm-project/pull/73099