[llvm] [InstrRef] Preserve debug instr num in aarch64-expand-pseudo LOADgot expansion (PR #128081)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse approved this pull request.

LGTM; realistically we can drop the bodies of most of the functions in the IR block, and the MIR can be generated with `--simplify-mir` to cut down the number of redundant lines expressing default values. To be absolutely minimal you could probably drop all but the final MIR blocks (I don't think llc will need them for the `LOADgot` instruction, only a declare in the LLVM-IR block?).

https://github.com/llvm/llvm-project/pull/128081