[llvm] [SPIR-V] Fix lowering of declarations with hidden visibility (PR #185029)

[Steven Perron via llvm-commits]

https://github.com/s-perron commented:

I think this is okay with us. However, I'm wondering why we need the check for isShaderLibrary. I wonder this is will only gloss over an error in the llvm-ir from the FE. 

https://github.com/llvm/llvm-project/pull/185029