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

[Rainer Orth via llvm-commits]

rorth wrote:

This patch broke the [Solaris/sparcv9 buildbot](https://lab.llvm.org/buildbot/#/builders/13/builds/5103).

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