[clang] Add support for anyAppleOS availability (PR #181953)

[Allan Shortlidge via cfe-commits]

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@@ -1113,6 +1113,7 @@ def Availability : InheritableAttr {
              .Case("maccatalyst_app_extension", "macCatalyst (App Extension)")
              .Case("xros", "visionOS")
              .Case("xros_app_extension", "visionOS (App Extension)")
+             .Case("anyappleos", "any Apple OS")
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tshortli wrote:

I don't think we should add support for app extension availability. Use of app extension specific availability has been discouraged as of late. If we could remove the concept of app extension availability from Swift, we probably would.

https://github.com/llvm/llvm-project/pull/181953