[clang] [Serialization] Fix crash while lazy-loading template specializations (PR #150430)

[Michael Jabbour via cfe-commits]

michael-jabbour-sonarsource wrote:

Thank you all for the reviews. I don’t have commit access, so I’ll need someone to merge this for me eventually. I’ll be away for the next week and won’t be able to respond to any regressions or follow-ups during that time.

If you’re comfortable merging it as is, please feel free to do so. Otherwise, I’ll ask for a merge when I’m back.

https://github.com/llvm/llvm-project/pull/150430