Fix Friflo SystemWithThreeComponents bug

Author: itsBuggingMe

source/Ecs.CSharp.Benchmark/SystemWithThreeComponents/FrifloEngineEcs.cs

@@ -56,7 +56,7 @@ public void FrifloEngineEcs_MultiThread()
 
         private static void Update(ref Component1 c1, ref Component2 c2, ref Component3 c3)
         {
-            c1.Value = c2.Value + c3.Value;
+            c1.Value += c2.Value + c3.Value;
         }
 
         [BenchmarkCategory(Categories.FrifloEngineEcs)]
@@ -72,10 +72,12 @@ public void FrifloEngineEcs_SIMD_MonoThread()
                 int step = component1.StepSpan256;                          // step = 8
                 for (int n = 0; n < component1Span.Length; n += step)
                 {
+                    Span<int> component3Slice = component3Span.Slice(n, step);
                     Vector256<int> value1 = Vector256.Create<int>(component1Span.Slice(n, step));
                     Vector256<int> value2 = Vector256.Create<int>(component2Span.Slice(n, step));
-                    Vector256<int> result = Vector256.Add(value1, value2);  // execute 8 add instructions at once
-                    result.CopyTo(component3Span.Slice(n, step));
+                    Vector256<int> value3 = Vector256.Create<int>(component3Slice);
+                    Vector256<int> result = Vector256.Add(value3, Vector256.Add(value1, value2));  // execute 16 add instructions
+                    result.CopyTo(component3Slice);
                 }
             }
         }