[clang] [llvm] [C++23] [CLANG] Adding C++23 constexpr math functions: fmin, fmax and frexp. (PR #88978)

[Zahira Ammarguellat via cfe-commits]

zahiraam wrote:

All the LIT tests failing are due to the latest changes I made. I will edit them once I know that the latest implementation is correct. 

https://github.com/llvm/llvm-project/pull/88978