Add shadows_disabled macro in Compatibility renderer

(cherry picked from commit 716fd3edfc0512ac434adb9750530b15ae3f8511)

drivers/gles3/shaders/scene.glsl

@@ -1611,6 +1611,8 @@ void main() {
 
 #if !defined(ADDITIVE_OMNI) && !defined(ADDITIVE_SPOT)
 
+#ifndef SHADOWS_DISABLED
+
 // Orthogonal shadows
 #if !defined(LIGHT_USE_PSSM2) && !defined(LIGHT_USE_PSSM4)
 	float directional_shadow = sample_shadow(directional_shadow_atlas, directional_shadows[directional_shadow_index].shadow_atlas_pixel_size, shadow_coord);
@@ -1717,6 +1719,9 @@ void main() {
 	directional_shadow = mix(directional_shadow, 1.0, smoothstep(directional_shadows[directional_shadow_index].fade_from, directional_shadows[directional_shadow_index].fade_to, vertex.z));
 	directional_shadow = mix(1.0, directional_shadow, directional_lights[directional_shadow_index].shadow_opacity);
 
+#else
+	float directional_shadow = 1.0f;
+#endif // SHADOWS_DISABLED
 	light_compute(normal, normalize(directional_lights[directional_shadow_index].direction), normalize(view), directional_lights[directional_shadow_index].size, directional_lights[directional_shadow_index].color * directional_lights[directional_shadow_index].energy, true, directional_shadow, f0, roughness, metallic, 1.0, albedo, alpha,
 #ifdef LIGHT_BACKLIGHT_USED
 			backlight,
@@ -1736,11 +1741,12 @@ void main() {
 #endif // !defined(ADDITIVE_OMNI) && !defined(ADDITIVE_SPOT)
 
 #ifdef ADDITIVE_OMNI
+	float omni_shadow = 1.0f;
+#ifndef SHADOWS_DISABLED
 	vec3 light_ray = ((positional_shadows[positional_shadow_index].shadow_matrix * vec4(shadow_coord.xyz, 1.0))).xyz;
-
-	float omni_shadow = texture(omni_shadow_texture, vec4(light_ray, length(light_ray) * omni_lights[omni_light_index].inv_radius));
+	omni_shadow = texture(omni_shadow_texture, vec4(light_ray, length(light_ray) * omni_lights[omni_light_index].inv_radius));
 	omni_shadow = mix(1.0, omni_shadow, omni_lights[omni_light_index].shadow_opacity);
-
+#endif // SHADOWS_DISABLED
 	light_process_omni(omni_light_index, vertex, view, normal, f0, roughness, metallic, omni_shadow, albedo, alpha,
 #ifdef LIGHT_BACKLIGHT_USED
 			backlight,
@@ -1759,9 +1765,11 @@ void main() {
 #endif // ADDITIVE_OMNI
 
 #ifdef ADDITIVE_SPOT
-	float spot_shadow = sample_shadow(spot_shadow_texture, positional_shadows[positional_shadow_index].shadow_atlas_pixel_size, shadow_coord);
+	float spot_shadow = 1.0f;
+#ifndef SHADOWS_DISABLED
+	spot_shadow = sample_shadow(spot_shadow_texture, positional_shadows[positional_shadow_index].shadow_atlas_pixel_size, shadow_coord);
 	spot_shadow = mix(1.0, spot_shadow, spot_lights[spot_light_index].shadow_opacity);
-
+#endif // SHADOWS_DISABLED
 	light_process_spot(spot_light_index, vertex, view, normal, f0, roughness, metallic, spot_shadow, albedo, alpha,
 #ifdef LIGHT_BACKLIGHT_USED
 			backlight,