Cycles: Cleanup, indent nested preprocessor directives

Quite straightforward, main trick is happening in path_source_replace_includes().

Reviewers: brecht, dingto, lukasstockner97, juicyfruit

Differential Revision: https://developer.blender.org/D1794

intern/cycles/kernel/kernel_path_surface.h

@@ -31,9 +31,9 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light(KernelGlobal
 	BsdfEval L_light;
 	bool is_lamp;
 
-#ifdef __OBJECT_MOTION__
+#  ifdef __OBJECT_MOTION__
 	light_ray.time = ccl_fetch(sd, time);
-#endif
+#  endif
 
 	if(sample_all_lights) {
 		/* lamp sampling */