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

[Tom Tromey via llvm-commits]

tromey wrote:

> Oh, out of curiosity: What's the motivation for this support?

It is twofold.  First this particular patch enables 128-bit discriminants in Rust.  I'm not sure how crucial this is, but anyway I stumbled across this because I'm improving the DWARF generation for Ada and it also needs the ability to add large constant attributes to a DIE.

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