[lit] Fix errors on wasm32-wasi

[yamt]

Summary

This fixes errors like:

fatal: Could not turn 'wasm32-wasi' into Itanium ABI triple

llvm/utils/lit/lit/llvm/config.py

def get_clang_has_lsan(self, clang, triple):
             if "Apple LLVM" in version_string or "Apple clang" in version_string:
                 # Apple clang doesn't yet support LSan
                 return False
             return major_version_number >= 5
 
         return False
 
     def make_itanium_abi_triple(self, triple):
+        if triple == "wasm32-wasi":
+            return triple
         m = re.match(r"(\w+)-(\w+)-(\w+)", triple)
         if not m:
             self.lit_config.fatal(
                 "Could not turn '%s' into Itanium ABI triple" % triple
             )
         if m.group(3).lower() != "windows":
             # All non-windows triples use the Itanium ABI.
             return triple
         return m.group(1) + "-" + m.group(2) + "-" + m.group(3) + "-gnu"
 
     def make_msabi_triple(self, triple):
+        if triple == "wasm32-wasi":
+            return triple
         m = re.match(r"(\w+)-(\w+)-(\w+)", triple)
         if not m:
             self.lit_config.fatal("Could not turn '%s' into MS ABI triple" % triple)
         isa = m.group(1).lower()
         vendor = m.group(2).lower()
         os = m.group(3).lower()
         if os == "windows" and re.match(r".*-msvc$", triple):
             # If the OS is windows and environment is msvc, we're done.