Fix T50550: GPUShader: compile error - Background image not showing in

viewport.

Caused by rBd6cf28c5e15739f864fbf04614c2a50708b4b152, which forgot to
update the GLSL code for the "Light Path" node.

source/blender/gpu/shaders/gpu_shader_material.glsl

@@ -3527,6 +3527,8 @@ void node_light_path(
 	out float is_transmission_ray,
 	out float ray_length,
 	out float ray_depth,
+	out float diffuse_depth,
+	out float glossy_depth,
 	out float transparent_depth,
 	out float transmission_depth)
 {
@@ -3539,6 +3541,8 @@ void node_light_path(
 	is_transmission_ray = 0.0;
 	ray_length = 1.0;
 	ray_depth = 1.0;
+	diffuse_depth = 1.0;
+	glossy_depth = 1.0;
 	transparent_depth = 1.0;
 	transmission_depth = 1.0;
 }