[clang] [Clang][Sema]: Allow copy constructor side effects (PR #81127)

[Vinayak Dev via cfe-commits]

vinayakdsci wrote:

@AaronBallman C++17 and later mark all of these constructor calls as _non_-elidable after ignoring the implicit casts, while C++14 and before mark the constructor that is assigned by `=` as elidable, and hence the warning. Should the constructor also be marked as elidable in C++ 17 and later, or not marked as elidable in C++14 and earlier?

https://github.com/llvm/llvm-project/pull/81127