[llvm] [Patchpoint] Add immarg attributes to patchpoint arguments (PR #97276)

[Csanád Hajdú via llvm-commits]

Il-Capitano wrote:

@sanjoy @preames @arsenm Can I ask for review of this PR, or can you add appropriate reviewers? There hasn't been much development on this part of LLVM in the past years, so it's hard to find reviewers, and I think this is a fairly trivial bugfix. Thanks!

https://github.com/llvm/llvm-project/pull/97276