Add missing #ifndef _3D_DISABLED to main file

XR is disabled when 3D is disbled so there is no sense in
setting xr specific settings and adding `--xr-mode` option

Signed-off-by: Yevhen Babiichuk (DustDFG) <dfgdust@gmail.com>

Author: dustdfg

main/main.cpp

@@ -612,7 +612,9 @@ void Main::print_help(const char *p_binary) {
 	print_help_option("--position <X>,<Y>", "Request window position.\n");
 	print_help_option("--screen <N>", "Request window screen.\n");
 	print_help_option("--single-window", "Use a single window (no separate subwindows).\n");
+#ifndef _3D_DISABLED
 	print_help_option("--xr-mode <mode>", "Select XR (Extended Reality) mode [\"default\", \"off\", \"on\"].\n");
+#endif
 
 	print_help_title("Debug options");
 	print_help_option("-d, --debug", "Debug (local stdout debugger).\n");
@@ -2558,6 +2560,7 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	GLOBAL_DEF("display/window/ios/hide_status_bar", true);
 	GLOBAL_DEF("display/window/ios/suppress_ui_gesture", true);
 
+#ifndef _3D_DISABLED
 	// XR project settings.
 	GLOBAL_DEF_RST_BASIC("xr/openxr/enabled", false);
 	GLOBAL_DEF_BASIC(PropertyInfo(Variant::STRING, "xr/openxr/default_action_map", PROPERTY_HINT_FILE, "*.tres"), "res://openxr_action_map.tres");
@@ -2586,7 +2589,8 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	// editor settings (it seems we're too early in the process when setting up rendering, to access editor settings...)
 	// EDITOR_DEF_RST("xr/openxr/in_editor", false);
 	// GLOBAL_DEF("xr/openxr/in_editor", false);
-#endif
+#endif // TOOLS_ENABLED
+#endif // _3D_DISABLED
 
 	Engine::get_singleton()->set_frame_delay(frame_delay);