shader: keep fragment layer values under lane masks

Co-authored-by: shadowbeat070 <70843316+shadowbeat070@users.noreply.github.com>

src/graphics/shader/shader.h

@@ -125,6 +125,7 @@ struct ShaderPixelInputInfo {
 	bool                                           ps_pos_z                     = false;
 	bool                                           ps_pos_w                     = false;
 	bool                                           ps_front_face                = false;
+	bool                                           ps_ancillary                 = false;
 	bool                                           ps_no_perspective            = false;
 	bool                                           ps_pixel_kill_enable         = false;
 	bool                                           ps_depth_export_enable       = false;