[libunwind] [libunwind] Enable wasm target for exceptions (PR #168449)

[Yerzhan Zhamashev via cfe-commits]

yerzham wrote:

I needed to clarify wasi-sdk had to use latest version of src/llvm-project, at least I tested since v21.1.5. Otherwise, usage of NO_EXEC_STACK_DIRECTIVE in UnwindRegistersRestore.S should be gated out since https://github.com/llvm/llvm-project/pull/92192 (then some modification at https://github.com/llvm/llvm-project/pull/162581). I do not think NO_EXEC_STACK_DIRECTIVE is ever used for wasm target after that, so it would be an unused declaration. As for the consequent errors, probably still related to outdated llvm source?

https://github.com/llvm/llvm-project/pull/168449