[llvm] [ADT] Deprecate StringRef::equals (PR #92351)

[Fangrui Song via llvm-commits]

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@@ -161,7 +161,9 @@ namespace llvm {
 
     /// equals - Check for string equality, this is more efficient than
     /// compare() when the relative ordering of inequal strings isn't needed.
-    [[nodiscard]] bool equals(StringRef RHS) const {
+    [[nodiscard]] LLVM_DEPRECATED(
+        "Use operator==(StringRef, StringRef) instead",
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MaskRay wrote:

Perhaps just `Use == instead`.

We don't expect users to write `operator==`

https://github.com/llvm/llvm-project/pull/92351