[llvm] [llvm][support] Refactor symlink handling and add readlink (PR #184256)

[Michael Spencer via llvm-commits]

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@@ -445,6 +443,13 @@ std::error_code create_link(const Twine &to, const Twine &from) {
   return std::error_code();
 }
 
+std::error_code create_link(const Twine &to, const Twine &from) {
+  std::error_code EC = create_symlink(to, from);
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Bigcheese wrote:

I changed it to be consistent and because existing uses of it should be ok with it being a hard link (as it would be on Windows before this change). The only reason I can think of that this would cause problems is just how rare creating a hard link would be, and that possibly messing up what other code assumes is happening.

https://github.com/llvm/llvm-project/pull/184256