[llvm] AMDGPU: Improve vector of pointer handling in amdgpu-promote-alloca (PR #114144)

[Matt Arsenault via llvm-commits]

arsenm wrote:

### Merge activity

* **Nov 6, 11:43 AM EST**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/114144).


https://github.com/llvm/llvm-project/pull/114144