Fix HashLengthInBytes to use instance property instead of static access

Co-authored-by: baronfel <573979+baronfel@users.noreply.github.com>

Author: Copilot

src/Tasks/Microsoft.NET.Build.Tasks/GenerateDepsFile.cs

@@ -266,8 +266,11 @@ bool ShouldIncludeRuntimeAsset(ITaskItem item)
             // If file exists, check if content is different using streaming hash comparison
             if (File.Exists(depsFilePath))
             {
+                // Get hash length from instance
+                var hashLength = new XxHash64().HashLengthInBytes;
+                
                 // Hash existing file content using streaming approach
-                Span<byte> existingHashBuffer = stackalloc byte[XxHash64.HashLengthInBytes];
+                Span<byte> existingHashBuffer = stackalloc byte[hashLength];
                 var existingHasher = new XxHash64();
                 using (var existingStream = File.OpenRead(depsFilePath))
                 {
@@ -276,7 +279,7 @@ bool ShouldIncludeRuntimeAsset(ITaskItem item)
                 existingHasher.GetCurrentHash(existingHashBuffer);
 
                 // Hash new content using streaming approach
-                Span<byte> newHashBuffer = stackalloc byte[XxHash64.HashLengthInBytes];
+                Span<byte> newHashBuffer = stackalloc byte[hashLength];
                 var newHasher = new XxHash64();
                 contentStream.Position = 0;
                 newHasher.Append(contentStream);

src/Tasks/Microsoft.NET.Build.Tasks/GenerateRuntimeConfigurationFiles.cs

@@ -408,8 +408,11 @@ private static void WriteToJsonFile(string fileName, object value)
             // If file exists, check if content is different using streaming hash comparison
             if (File.Exists(fileName))
             {
+                // Get hash length from instance
+                var hashLength = new XxHash64().HashLengthInBytes;
+                
                 // Hash existing file content using streaming approach
-                Span<byte> existingHashBuffer = stackalloc byte[XxHash64.HashLengthInBytes];
+                Span<byte> existingHashBuffer = stackalloc byte[hashLength];
                 var existingHasher = new XxHash64();
                 using (var existingStream = File.OpenRead(fileName))
                 {
@@ -418,7 +421,7 @@ private static void WriteToJsonFile(string fileName, object value)
                 existingHasher.GetCurrentHash(existingHashBuffer);
 
                 // Hash new content using streaming approach
-                Span<byte> newHashBuffer = stackalloc byte[XxHash64.HashLengthInBytes];
+                Span<byte> newHashBuffer = stackalloc byte[hashLength];
                 var newHasher = new XxHash64();
                 contentStream.Position = 0;
                 newHasher.Append(contentStream);