[clang] [APINotes] Upstream Sema logic to apply API Notes to decls (PR #78445)

[Nikita Popov via cfe-commits]

nikic wrote:

FYI this change adds some overhead (about 0.2% for O0) builds (http://llvm-compile-time-tracker.com/compare.php?from=046682ef88a254443e8620bfd48b35bfa0a83809&to=440b1743ee0c8bfb7bf0c4b503bde5ab9af88dc0&stat=instructions:u). Is it possible to avoid it for people not using API notes?

https://github.com/llvm/llvm-project/pull/78445