[lld] [LLD][COFF] Avoid resolving symbols with -alternatename if the target is undefined (PR #149496)

[Jacek Caban via llvm-commits]

cjacek wrote:

Depends on #149495, which enables the use of `forceLazy` here.
Without it, we could fall back to `addUndefined`, but since the symbol is already available, there's no need to perform an additional lookup.

https://github.com/llvm/llvm-project/pull/149496