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

[Martin Storsjö via cfe-commits]

mstorsjo wrote:

I also bisected errors on Windows, down to this commit.

The errors show up when running the compiler-rt testsuite, like this: https://github.com/mstorsjo/llvm-mingw/actions/runs/11356888872/job/31598676534
A number of tests fail, where `llvm-cov` errors out with `profile uses zlib compression but the profile reader was built without zlib support`.

This can be reproduced with something as small as `llvm-cov show coverage_comments.cpp.exe -instr-profile coverage_comments.cpp.tmp.profdata`. Binaries of `llvm-cov` from before this change work fine, while binaries from after it produce this error.

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