prefer HashCode when possible

Author: mgravell

src/Caching/Hybrid/src/Internal/DefaultHybridCache.StampedeKey.cs

@@ -17,7 +17,11 @@ public StampedeKey(string key, HybridCacheEntryFlags flags)
         {
             _key = key;
             _flags = flags;
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+            _hashCode = HashCode.Combine(key, flags);
+#else
             _hashCode = key.GetHashCode() ^ (int)flags;
+#endif
         }
 
         public string Key => _key;

src/Caching/Hybrid/src/Microsoft.Extensions.Caching.Hybrid.csproj

@@ -4,7 +4,7 @@
     <Description>Multi-level caching implementation building on and extending IDistributedCache</Description>
     <!--
       relevant TFM feature summary (all "nice to have", with reasonable workarounds):
-        nca 2.0 / ns 2.1: RuntimeHelpers.IsReferenceOrContainsReferences; Task.IsCompletedSuccessfully
+        nca 2.0 / ns 2.1: RuntimeHelpers.IsReferenceOrContainsReferences; Task.IsCompletedSuccessfully; HashCode
         nca 3.0 : IThreadPoolWorkItem
         net 5.0 : [DynamicallyAccessedMembers], EncodingExtensions.GetString/GetBytes, IsExternalInit
         net 7.0 : ArgumentNullException.ThrowIfNull