opt: optimize keymap set

src/config/preset.h

@@ -123,6 +123,10 @@ static const struct xkb_rule_names xkb_fallback_rules = {
 	.options = NULL,
 };
 
+static const struct xkb_rule_names xkb_default_rules = {
+	.options = NULL,
+};
+
 struct xkb_rule_names xkb_rules = {
 	/* can specify fields: rules, model, layout, variant, options */
 	/* example:

src/dispatch/bind_define.h

@@ -865,7 +865,7 @@ int switch_keyboard_layout(const Arg *arg) {
 	if (!check_keyboard_rules_validate(&rules)) {
 		wlr_log(WLR_ERROR,
 				"Keyboard rules validation failed, skipping layout reset");
-		rules = xkb_fallback_rules;
+		rules = xkb_default_rules;
 	}
 
 	char *layout_buf = (char *)rules.layout; // 假设这是可修改的

src/mango.c

@@ -2377,7 +2377,7 @@ KeyboardGroup *createkeyboardgroup(void) {
 	if (!check_keyboard_rules_validate(&rules)) {
 		wlr_log(WLR_ERROR,
 				"Keyboard rules validation failed, skipping layout reset");
-		rules = xkb_fallback_rules;
+		rules = xkb_default_rules;
 	}
 
 	/* Prepare an XKB keymap and assign it to the keyboard group. */
@@ -4633,7 +4633,7 @@ void reset_keyboard_layout(void) {
 	if (!check_keyboard_rules_validate(&rules)) {
 		wlr_log(WLR_ERROR,
 				"Keyboard rules validation failed, skipping layout reset");
-		rules = xkb_fallback_rules;
+		rules = xkb_default_rules;
 	}
 
 	// Create context