Roll engine 4b391cbe7e0a..5429f40bf8c1 (2 commits) (#34936)

https://github.com/flutter/engine/compare/4b391cbe7e0a...5429f40bf8c1

git log 4b391cbe7e0a4c02fb46e7131749c9c5714bfbc4..5429f40bf8c1fed4d6bdcb981b94eac02903b9d5 --no-merges --oneline
5429f40bf Revert "Roll fuchsia/sdk/core/mac-amd64 from Cx51FRV5TCoqQ9nfs4E2QMfYkJ1JWt7arQXhV01tr7cC to e8sS_5Rpuo7cSjSWPCdxwTEAg2VbS9NPH2tjhBhPwsUC (#9442)" (flutter/engine#9446)
38078dfcd Roll fuchsia/sdk/core/mac-amd64 from Cx51FRV5TCoqQ9nfs4E2QMfYkJ1JWt7arQXhV01tr7cC to e8sS_5Rpuo7cSjSWPCdxwTEAg2VbS9NPH2tjhBhPwsUC (flutter/engine#9442)

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bin/internal/engine.version

-4b391cbe7e0a4c02fb46e7131749c9c5714bfbc4
+5429f40bf8c1fed4d6bdcb981b94eac02903b9d5