[clang] [WIP] [Modules] Delay reading type source info of the preferred_name attribute. (PR #122250)

[Chuanqi Xu via cfe-commits]

https://github.com/ChuanqiXu9 commented:

A special handling for `PreferredName` looks slightly add-hoc to me. What I thought is to delay the deserialization of `attributes` after the deserialization of the declaration. If this is too optimistic, I am wondering if we can delay reading of some sorts of attributes only, which is more generic.

https://github.com/llvm/llvm-project/pull/122250