[llvm] [flang-rt] Optimise ShallowCopy and use it in CopyInAssign (PR #140569)

[Valentin Clement バレンタイン クレメン via llvm-commits]

clementval wrote:

> kNoAsyncId changed to kNoAsyncObject 2-3 days ago hence the failures, I already merged a fix.

Always make sure that the pre commit ci pass before merging. 

https://github.com/llvm/llvm-project/pull/140569