[llvm] [OpenMP][OpenMPIRBuilder][NFC] Move copyInput to a passed in lambda function (PR #68124)

[via llvm-commits]

agozillon wrote:

Thank you very much for the review guys! 

I'll give @jsjodin sometime to review it if he wishes as he wrote it originally, and incase @jdoerfert wishes to give any input as well. Neither are required if you do not wish to spend the time reviewing though (as I'm aware everyone's time is precious and people are likely preparing to go to the conference next week), but I'll leave the patch open until Friday afternoon/evening (UK time) just incase! 

https://github.com/llvm/llvm-project/pull/68124