[lld] [ELF] Respect orders of symbol assignments and DEFINED (PR #65866)

[Peter Smith via llvm-commits]

https://github.com/smithp35 approved this pull request.

I took a (very) quick look at GNU, it appears to have a statement counter that is used for a similar purpose.

Only got a couple of small comments so marking approved.

https://github.com/llvm/llvm-project/pull/65866