[llvm] [TBAA] Do not rewrite TBAA tag in `adjustForAccess` if already exists (PR #96483)

[Florian Hahn via llvm-commits]

fhahn wrote:

So the issue here is that clang generates legacy tbaa tags for tbaa.struct while the !tbaa tags are the struct-path format? Is there any reason that clang shouldn't emit struct-path tags for !tbaa.struct?

https://github.com/llvm/llvm-project/pull/96483