[lld] [lld][WebAssembly] Match the ELF linker in transitioning away from archive indexes. (PR #78658)

[Alex Crichton via llvm-commits]

alexcrichton wrote:

Last I tested even unferenced files with custom sections still had their custom sections included in the output. Testing now though that appears to at least no longer be the case so putting the metadata in a custom section would work, except for `--whole-archive` like you mention. However I don't believe rustc ever uses `--whole-archive` for rlibs, only other user-provided things, so I believe that using custom sections for this should suffice well. I'll work on getting that into rustc!

https://github.com/llvm/llvm-project/pull/78658