[clang] [compiler-rt] [lld] [llvm] [Coverage][WebAssembly] Add initial support for WebAssembly/WASI (PR #111332)

[Yuta Saito via llvm-commits]

kateinoigakukun wrote:

@arsnyder16 The feature itself has already been in the main, and we are using the feature in Swift https://book.swiftwasm.org/getting-started/testing.html#code-coverage-with-swiftpm

I think we don't need extra change in `llvm-profdata` and `llvm-cov` for Emscripten support, but we need some changes for libcompiler_rt.profile.a to port it to Emscripten.

https://github.com/llvm/llvm-project/pull/111332