[clang] [libunwind] [llvm] [wasm] Toolchain support for `wasm32-wali-linux-musl` target (PR #156087)

[Arjun Ramesh via llvm-commits]

================
@@ -199,6 +199,7 @@ class Triple {
     SUSE,
     OpenEmbedded,
     Intel,
+    WALI,
----------------
arjunr2 wrote:

We're really not adding a new OS to the set of triples here since we're reusing Linux, just the new ABI for Wasm.

It's not too late to modify the rustc, but notably, that will not really be pratically since right now, having the rustc target with `wasm32`, `linux`, and `musl` allows minimal patching across crates by reusing existing cfg environments. Hence the decision to opt for just the vendor field in Rust -- changing the environment to something else will be a huge pain 

https://github.com/llvm/llvm-project/pull/156087