[llvm] Allow 128-bit discriminants in DWARF variants (PR #125578)

[David Blaikie via llvm-commits]

dwblaikie wrote:

> This is mostly implemented by copying DwarfUnit::addConstantValue. However, I did not reimplement that method in terms of the new addInt because that would introduce the need for unrelated test case changes.

I think that's probably still the right path - what unrelated test changes did you discover down this path?

Potentially doing this in two steps, even - one, an API change to `DwarfUnit::addConstantValue` take the `DW_AT_` to use as a parameter. That change shouldn't cause any change to LLVM's behavior.

Then, after that, we could reuse the function from this new location.

https://github.com/llvm/llvm-project/pull/125578