VideoBackends: add support to allow rendering to multiple output textures

Source/Core/VideoBackends/D3D/D3DGfx.h

@@ -41,7 +41,8 @@ public:
                                                    const void* cache_data = nullptr,
                                                    size_t cache_data_length = 0) override;
   std::unique_ptr<AbstractFramebuffer>
-  CreateFramebuffer(AbstractTexture* color_attachment, AbstractTexture* depth_attachment) override;
+  CreateFramebuffer(AbstractTexture* color_attachment, AbstractTexture* depth_attachment,
+                    std::vector<AbstractTexture*> additional_color_attachments) override;
 
   void SetPipeline(const AbstractPipeline* pipeline) override;
   void SetFramebuffer(AbstractFramebuffer* framebuffer) override;