[clang] [clang][clang-cl] Add -fms-preprocessor-compat and support /Zc:preprocessor (PR #167200)

[Corentin Jabot via cfe-commits]

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@@ -269,6 +269,7 @@ LANGOPT(HIPStdParInterposeAlloc, 1, 0, NotCompatible, "Replace allocations / dea
 
 LANGOPT(OpenACC           , 1, 0, NotCompatible, "OpenACC Enabled")
 
+LANGOPT(MSVCPreprocessor , 1, 0, NotCompatible, "Fully emulate the Microsoft Visual C++ traditional (non-conforming) preprocessor")
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cor3ntin wrote:

```suggestion
LANGOPT(MSVCPreprocessor , 1, 0, NotCompatible, "Emulate the Microsoft Visual C++ traditional (non-conforming) preprocessor")
```

https://github.com/llvm/llvm-project/pull/167200