[clang] [clang]: baremetal `multilib.yaml` discovery (PR #227965)

[Mythreya Kuricheti via cfe-commits]

================
@@ -202,10 +202,10 @@ ToolChain::findMultilibsYAML(const llvm::opt::ArgList &Args, const Driver &D,
   }
 
   SmallString<128> MultilibPath;
-  if (!FallbackDir.empty())
-    MultilibPath = FallbackDir;
-  else if (std::optional<std::string> StdlibDir = getStdlibPath())
+  if (std::optional<std::string> StdlibDir = getStdlibPath())
----------------
MythreyaK wrote:

> It never really checks if the yaml file is actually there.

Ah whoops :see_no_evil:! I'll make that change, thanks. 

https://github.com/llvm/llvm-project/pull/227965