[clang] [Clang][NFC] Remove duplicated specialization of `llvm::DenseMapInfo<llvm::FoldingSetNodeID>` (PR #159718)

[Younan Zhang via cfe-commits]

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@@ -3843,4 +3843,25 @@ typename clang::LazyGenerationalUpdatePtr<Owner, T, Update>::ValueType
   return Value;
 }
 
+template <> struct llvm::DenseMapInfo<llvm::FoldingSetNodeID> {
+  static FoldingSetNodeID getEmptyKey() { return FoldingSetNodeID{}; }
+
+  static FoldingSetNodeID getTombstoneKey() {
+    FoldingSetNodeID ID;
+    for (size_t I = 0; I < sizeof(ID) / sizeof(unsigned); ++I) {
+      ID.AddInteger(std::numeric_limits<unsigned>::max());
+    }
+    return ID;
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zyn0217 wrote:

@cor3ntin

https://github.com/llvm/llvm-project/pull/159718