[clang] [clang][modules] Built-in modules are not correctly enabled for Mac Catalyst (PR #104872)

[Cyndy Ishida via cfe-commits]

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@@ -2953,7 +2953,15 @@ static bool sdkSupportsBuiltinModules(
   case Darwin::MacOS:
     return SDKVersion >= VersionTuple(15U);
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cyndyishida wrote:

The extra test coverage is more for future-proofing. There is a decent amount of `TargetVariantTriple` logic happening in this file. 

https://github.com/llvm/llvm-project/pull/104872