[llvm] [ADT] Update hash function of uint64_t for DenseMap (PR #95734)

[Fangrui Song via llvm-commits]

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@@ -151,7 +151,8 @@ template<> struct DenseMapInfo<unsigned long long> {
   static inline unsigned long long getTombstoneKey() { return ~0ULL - 1ULL; }
 
   static unsigned getHashValue(const unsigned long long& Val) {
-    return (unsigned)(Val * 37ULL);
+    return DenseMapInfo<unsigned>::getHashValue(Val) ^
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MaskRay wrote:

the easy way is `detail::combineHashValue`

https://github.com/llvm/llvm-project/pull/95734