[llvm] [IR] Allow uses of `llvm.global_ctors` and `llvm.global_dtors` (PR #96477)

[Nikita Popov via llvm-commits]

nikic wrote:

@kovdan01 Can you use some special value as the discriminator to indicate to the backend that you want a self-reference? That way only the backend has to deal with it.

https://github.com/llvm/llvm-project/pull/96477