[lld] [ELF] Infer EI_OSABI from object files (PR #97144)

[John Ericson via llvm-commits]

https://github.com/Ericson2314 approved this pull request.

Great idea! I forgot that -- duh -- the input objects also have OSABI fields.

https://github.com/llvm/llvm-project/pull/97144