[llvm] [Object] Provide operator< for ELFSymbolRef (PR #89861)

[James Henderson via llvm-commits]

jh7370 wrote:

I've not really looked myself, but are there instances where you actually have two ELFSymbolRef objects that are compared (using `<`)? If not, this code is dead, I believe. Also, is there a reason you provide `<` but not `==`? I note that `DataRefImpl` has both.

https://github.com/llvm/llvm-project/pull/89861