[lld] Enough LLD changes to bootstrap OpenBSD on sparc64 (PR #207609)

[Fangrui Song via llvm-commits]

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@@ -61,6 +61,7 @@ enum RelExpr {
   R_PLT_GOTPLT,
   R_PLT_GOTREL,
   R_RELAX_HINT,
+  R_RELAX_GOT_OFF,
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MaskRay wrote:

Can we do this the optimization without introducing a generic RelExpr member?

https://github.com/llvm/llvm-project/pull/207609