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

[Kajetan Puchalski via llvm-commits]

mrkajetanp wrote:

Ah right I see, it happens for me only on a gcc standalone flang-rt build. Running check-flang-rt within a full llvm build works fine. Standalone clang works fine too. That's pretty odd, I'll try to figure out where the problem is. 

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