The parser's `DeferredLocInfo` uses an uncommon TypeID setup, where it
defines a private TypeID for pointers to the struct.
When using the fallback TypeID mechanism introduced in
https://github.com/llvm/llvm-project/pull/126999, the fallback TypeID
mechanism doesn't support anonymous namespaces, and the
`INTERNAL_INLINE` mechanism doesn't support pointer types.
Explicitly use `SELF_OWNING_TYPE_ID` for this case. This should always
be safe for anonymous namespaces.
1618d09ce7