[lld] [ELF] Fix non-preemptible IFUNC IRELATIVE addends (PR #179037)

[Jessica Clarke via llvm-commits]

jrtc27 wrote:

If you think there is a bug, please provide a minimal assembly test case that this patch changes the behaviour of. Gesturing towards glibc's ld.so and saying "before it was wrong, now it is right" without explaining what actually you believe caused the problem doesn't help.

https://github.com/llvm/llvm-project/pull/179037