[clang] [clang] Predefine `_CRT_USE_BUILTIN_OFFSETOF` in MS-compatible modes (PR #127568)

[Aaron Ballman via cfe-commits]

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@@ -220,6 +220,8 @@ static void addVisualCDefines(const LangOptions &Opts, MacroBuilder &Builder) {
     Builder.defineMacro("_MSC_FULL_VER", Twine(Opts.MSCompatibilityVersion));
     // FIXME We cannot encode the revision information into 32-bits
     Builder.defineMacro("_MSC_BUILD", Twine(1));
+    // https://github.com/llvm/llvm-project/issues/59689
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AaronBallman wrote:

```suggestion
    // Exposed by MSVC, used in their stddef.h.
```

https://github.com/llvm/llvm-project/pull/127568