GPUMaterial: Remove unused Normal input.

source/blender/gpu/shaders/gpu_shader_material.glsl

@@ -2836,7 +2836,7 @@ void environment_default_vector(out vec3 worldvec)
 }
 #endif
 
-void node_background(vec4 color, float strength, vec3 N, out vec4 result)
+void node_background(vec4 color, float strength, out vec4 result)
 {
 	result = color * strength;
 }

source/blender/nodes/shader/nodes/node_shader_background.c

@@ -42,7 +42,7 @@ static bNodeSocketTemplate sh_node_background_out[] = {
 
 static int node_shader_gpu_background(GPUMaterial *mat, bNode *UNUSED(node), bNodeExecData *UNUSED(execdata), GPUNodeStack *in, GPUNodeStack *out)
 {
-	return GPU_stack_link(mat, "node_background", in, out, GPU_builtin(GPU_VIEW_NORMAL));
+	return GPU_stack_link(mat, "node_background", in, out);
 }
 
 /* node type definition */