[lld] [lld][COFF][LTO] Implement /opt:emitllvm option (PR #66964)

[Matheus Izvekov via llvm-commits]

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@@ -1822,6 +1822,8 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
         ltoDebugPM = true;
       } else if (s == "noltodebugpassmanager") {
         ltoDebugPM = false;
+      } else if (s == "emitllvm") {
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mizvekov wrote:

I thought about this, but the best argument I have got so far is that this matches the equivalent option for the ELF linker, where it's in the `--plugin-opt=` umbrella.

Sure, I can look into adding `emit-asm`.

https://github.com/llvm/llvm-project/pull/66964