[llvm] Added instant events and marking defered templated instantiation. (PR #103039)

[Utkarsh Saxena via llvm-commits]

https://github.com/usx95 approved this pull request.

Thanks for splitting the change.

Looks good to me. Left a nit to remove double negation.

Please fix the change description. I will land the change once these are done.

https://github.com/llvm/llvm-project/pull/103039