[llvm] ADT/Matrix: two-dimensional Container with View (PR #98893)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> Say you define a function:
> 
> ```c++
> constexpr int add(int a, int b) { return a + b; }
> ```
> 
> this won't make any runtime call to `add` faster but it will allow you to write `static_assert(add(2 + 3) == 5);` or use it in `SmallVector<float, add(3+4)> floats;`

Thanks for the explanation. I will remove the useless `constexpr` annotations, and drop the arrayref-constexpr patch.

https://github.com/llvm/llvm-project/pull/98893