Use index fragment shader output when dual source blend is enabled (#4404)

* Use index fragment shader output when dual source blend is enabled

* Shader cache version bump

* Actually set DualSourceBlendEnabled to true

* Fix XML doc

---------

Co-authored-by: Ac_K <Acoustik666@gmail.com>

Ryujinx.Graphics.Gpu/Shader/DiskCache/DiskCacheGpuAccessor.cs

@@ -141,6 +141,12 @@ namespace Ryujinx.Graphics.Gpu.Shader.DiskCache
             return _oldSpecState.GraphicsState.HasConstantBufferDrawParameters;
         }
 
+        /// <inheritdoc/>
+        public bool QueryDualSourceBlendEnable()
+        {
+            return _oldSpecState.GraphicsState.DualSourceBlendEnable;
+        }
+
         /// <inheritdoc/>
         public InputTopology QueryPrimitiveTopology()
         {