Only include FSR2 wrapper plugin on Windows, where the original native plugin actually exists

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/RenderPass/Upscalers/FSR2WrapperUpscaler.cs

@@ -1,5 +1,6 @@
 using System;
 
+#if UNITY_STANDALONE_WIN
 namespace UnityEngine.Rendering.HighDefinition.AMD.FSR2Wrapper
 {
     /// <summary>
@@ -128,3 +129,4 @@ namespace UnityEngine.Rendering.HighDefinition.AMD.FSR2Wrapper
         }
     }
 }
+#endif  // UNITY_STANDALONE_WIN

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/RenderPass/Upscalers/UpscalerPlugin.cs

@@ -10,7 +10,9 @@ namespace UnityEngine.Rendering.HighDefinition.AMD
         private static readonly List<UpscalerPlugin> AvailablePlugins = new()
         {
             new FSR3.FSR3UpscalerPlugin(),
+#if UNITY_STANDALONE_WIN
             new FSR2Wrapper.FSR2WrapperUpscaler(),
+#endif
         };
         
         internal static UpscalerPlugin ActivePlugin = AvailablePlugins[0];