[clang] [APINotes] Upstream APINotesWriter (PR #65187)

[Egor Zhdan via cfe-commits]

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@@ -19,11 +19,11 @@
 
 namespace clang {
 namespace api_notes {
-class APINotesWriter::Implementation {
-  template <typename T>
-  using VersionedSmallVector =
-      llvm::SmallVector<std::pair<llvm::VersionTuple, T>, 1>;
+template <typename T>
+using VersionedSmallVector =
+    llvm::SmallVector<std::pair<llvm::VersionTuple, T>, 1>;
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egorzhdan wrote:

This is used in both `APINotesWriter` and `APINotesWriter::Implementation`.

https://github.com/llvm/llvm-project/pull/65187