[libcxxabi] [libunwind] [llvm] fix Wasm exceptions + coop threading + shared libraries (PR #222747)

[Heejin Ahn via cfe-commits]

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aheejin wrote:

Nit: We can add
```ll
; CHECK-DAG: declare ptr @_Unwind_GetWasmLPadContext()
```
here

https://github.com/llvm/llvm-project/pull/222747