[clang] [Serialization] Fix lazy template loading (PR #133057)

[Chuanqi Xu via cfe-commits]

https://github.com/ChuanqiXu9 approved this pull request.

BTW, I've landed the 3 patches (excluding the problematic reported by Google) internally and we've used it for months. It looks good.

https://github.com/llvm/llvm-project/pull/133057