[clang] [Matrix] Add a row\col major toggle in the clang driver (PR #167628)

[Florian Hahn via cfe-commits]

================
@@ -251,6 +251,13 @@ class LangOptionsBase {
     FEM_UnsetOnCommandLine = 3
   };
 
+  enum MatrixMemoryLayout : unsigned {
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fhahn wrote:

```suggestion
  enum class MatrixMemoryLayout : unsigned {
```

https://github.com/llvm/llvm-project/pull/167628