[llvm] [DirectX] Convert private global variables to internal linkage during Finalize Linkage pass (PR #146406)

[Kaitlin Peng via llvm-commits]

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kmpeng wrote:

Was also wondering that but I'm not familiar with how that works for these shaders. When I tested it locally the validation succeeded. 

@farzonl is there a way to add a test?

https://github.com/llvm/llvm-project/pull/146406