[clang] [Driver] Find vendor-prefixed musl GCC toolchains (PR #206477)

[Adeel Mujahid via cfe-commits]

================
@@ -538,9 +544,7 @@ Attribute Changes in Clang
   ISO 18037 fixed-point ``printf`` specifiers.
 
 - The ``const`` and ``pure`` attributes only apply to functions; they are now
-  diagnosed and ignored when applied to anything else. Additionally, calling
-  a function marked ``noreturn`` from a function marked ``const`` or ``pure``
-  is now diagnosed as undefined behavior (#GH129022).
+  diagnosed and ignored when applied to anything else.
----------------
am11 wrote:

```suggestion
  diagnosed and ignored when applied to anything else. Additionally, calling
  a function marked ``noreturn`` from a function marked ``const`` or ``pure``
  is now diagnosed as undefined behavior (#GH129022).
  diagnosed and ignored when applied to anything else.
```

https://github.com/llvm/llvm-project/pull/206477