[llvm] [Support] Add clang tooling generated explicit visibility macros (PR #113097)

[Thomas Fransham via llvm-commits]

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fsfod wrote:

Some of this is also discussed in @compnerds old thread  https://discourse.llvm.org/t/supporting-llvm-build-llvm-dylib-on-windows/58891

https://github.com/llvm/llvm-project/pull/113097