[llvm] [Dexter] Add label nodes for line references (PR #202544)

[Stephen Tozer via llvm-commits]

SLTozer wrote:

The merged commit looks to be causing failures in the pre-merge checks for AArch64 specifically, though maybe not entirely consistently (some builds it seems to pass, others it fails) - I'm not totally clear on why, since I've not tested the aarch64 configuration myself and we don't have an aarch64 buildbot running cross-project-tests; I think the best immediate course of action would be to set these tests to not run on aarch64, to prevent spurious errors appearing in pre-merge checks.

https://github.com/llvm/llvm-project/pull/202544