[clang] [clang] Fix the crash when dumping deserialized decls (PR #133395)

[Ilya Biryukov via cfe-commits]

================
@@ -27,6 +27,8 @@ class MacroInfo;
 class Module;
 class SourceLocation;
 
+// IMPORTANT: when you add a new interface to this class, please update the
+// DelegatingDeserializationListener in FrontendAction.cpp
----------------
ilya-biryukov wrote:

Future idea: maybe we could move the `DelegatingDeserializationListener` here or into the `Serialization` folder?
It is generic and not specific to `FrontendAction`, so it probably makes more sense to have it here, even if it's only used in `FrontendAction`. That makes changes like this more localized.

https://github.com/llvm/llvm-project/pull/133395