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

[Sam Clegg via llvm-commits]

sbc100 wrote:

I just did some investigation and found out why this is not and issue for the ELF rust toolchain: Their rlib.meta files are valid ELF objects:

```
$ objdump -h lib.rmeta 

lib.rmeta:	file format elf64-x86-64

Sections:
Idx Name               Size     VMA              Type
  0                    00000000 0000000000000000 
  1 .note.gnu.property 00000020 0000000000000000 
  2 .rmeta             00546bfa 0000000000000000 
  3 .symtab            00000018 0000000000000000 
  4 .strtab            00000001 0000000000000000 
  5 .shstrtab          00000035 0000000000000000 
```

If we want to fix this properly I guess we would need to do that same for wasm.. but the removal of `--fatal-warnings` should work too.  The downside is that since (IIUC) rustc hides the linker stderr by default that means rust users will no longer see the signature mismatch warnings that wasm-ld produces.  Not a huge deal perhaps..



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