[lld] [ELF] Add support for PT_OPENBSD_NOBTCFI (PR #120005)

[Fangrui Song via llvm-commits]

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@@ -1897,6 +1897,9 @@ static void setConfigs(Ctx &ctx, opt::InputArgList &args) {
       ErrAlways(ctx) << "cannot open --why-extract= file " << ctx.arg.whyExtract
                      << ": " << e.message();
   }
+
+  if (ctx.arg.osabi == ELFOSABI_OPENBSD)
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MaskRay wrote:

`ld.lld -z nobtcfi empty.o` has a false positive warning. Perhaps we need to move this variable back to readConfigs.

https://github.com/llvm/llvm-project/pull/120005