[llvm] [IRLinker] Don't add duplicate named MD node operand to dest module (PR #146020)

[Alexey Bader via llvm-commits]

bader wrote:

> Since that patch got stuck we've had [this pass](https://github.com/llvm/llvm-project/blob/60a18d611907dc904cd893a53c72b99c8e55ae06/llvm/lib/Target/AMDGPU/AMDGPUUnifyMetadata.cpp) to work around it.

Unfortunately, this problem is not unique to AMDGPU target. Do you think we should make unify-metadata pass target independent and run it for other targets as well (e.g. SPIR-V)?

https://github.com/llvm/llvm-project/pull/146020