[clang] [clang] Move `AvailabilityInfo` into AST library (PR #81897)

[Juergen Ributzka via cfe-commits]

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@@ -57,6 +58,57 @@ class AvailabilitySpec {
   bool isOtherPlatformSpec() const { return Version.empty(); }
 };
 
+class Decl;
+
+/// Storage of availability attributes for a declaration.
+struct AvailabilityInfo {
+  /// The domain is the platform for which this availability info applies to.
+  llvm::SmallString<32> Domain;
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ributzka wrote:

Are 32 chars required?

https://github.com/llvm/llvm-project/pull/81897