fix the keybind handling in rootston.

As mentioned in https://github.com/swaywm/wlroots/issues/393 keybinds
did't trigger / were checked with "odd" keys and modifiers.

This commit sends the keycode through two paths, one to get the keycode
and modifiers *after* xkb handles them, a secondary path to get a "raw"
keysym without modifiers and then add the modifiers rootston knows
about.

This will result in the `[Alt]+[Shift]+2` combination I mention earlier
going through the keybind detection twice.
  1) `[Alt]+[at]`
  2) `[Alt]+[Shift]+2`

When either combination is found, the appropriate keybind is executed.
The xkb handled version will be prefered over the "raw" version.

rootston/keyboard.c

@@ -60,7 +60,7 @@ static void keyboard_binding_execute(struct roots_keyboard *keyboard,
  * should be propagated to clients.
  */
 static bool keyboard_keysym_press(struct roots_keyboard *keyboard,
-		xkb_keysym_t keysym) {
+		xkb_keysym_t keysym, uint32_t modifiers) {
 	ssize_t i = keyboard_pressed_keysym_index(keyboard, keysym);
 	if (i < 0) {
 		i = keyboard_pressed_keysym_index(keyboard, XKB_KEY_NoSymbol);
@@ -88,7 +88,6 @@ static bool keyboard_keysym_press(struct roots_keyboard *keyboard,
 		wlr_seat_keyboard_end_grab(keyboard->input->wl_seat);
 	}
 
-	uint32_t modifiers = wlr_keyboard_get_modifiers(keyboard->device->keyboard);
 	struct wl_list *bindings = &keyboard->input->server->config->bindings;
 	struct binding_config *bc;
 	wl_list_for_each(bc, bindings, link) {
@@ -122,25 +121,70 @@ static void keyboard_keysym_release(struct roots_keyboard *keyboard,
 	}
 }
 
-static void keyboard_key_notify(struct wl_listener *listener, void *data) {
-	struct wlr_event_keyboard_key *event = data;
-	struct roots_keyboard *keyboard = wl_container_of(listener, keyboard, key);
+static bool keyboard_keysyms_simple(struct roots_keyboard *keyboard,
+		uint32_t keycode, enum wlr_key_state state)
+{
+	uint32_t modifiers = wlr_keyboard_get_modifiers(keyboard->device->keyboard);
+	const xkb_keysym_t *syms;
+	xkb_layout_index_t layout_index = xkb_state_key_get_layout(
+		keyboard->device->keyboard->xkb_state,
+		keycode);
+	int syms_len = xkb_keymap_key_get_syms_by_level(keyboard->device->keyboard->keymap,
+		keycode, layout_index, 0, &syms);
 
-	uint32_t keycode = event->keycode + 8;
+	bool handled = false;
+	for (int i = 0; i < syms_len; i++) {
+		if (state) {
+			bool keysym_handled = keyboard_keysym_press(keyboard,
+				syms[i], modifiers);
+			handled = handled || keysym_handled;
+		} else { // WLR_KEY_RELEASED
+			keyboard_keysym_release(keyboard, syms[i]);
+		}
+	}
+
+	return handled;
+}
+
+static bool keyboard_keysyms_xkb(struct roots_keyboard *keyboard,
+		uint32_t keycode, enum wlr_key_state state)
+{
+	uint32_t modifiers = wlr_keyboard_get_modifiers(keyboard->device->keyboard);
 	const xkb_keysym_t *syms;
 	int syms_len = xkb_state_key_get_syms(keyboard->device->keyboard->xkb_state,
 		keycode, &syms);
+	uint32_t consumed = xkb_state_key_get_consumed_mods2(
+		keyboard->device->keyboard->xkb_state,
+		keycode,
+		XKB_CONSUMED_MODE_XKB);
+
+	modifiers = modifiers & ~consumed;
 
 	bool handled = false;
 	for (int i = 0; i < syms_len; i++) {
-		if (event->state == WLR_KEY_PRESSED) {
-			bool keysym_handled = keyboard_keysym_press(keyboard, syms[i]);
+		if (state) {
+			bool keysym_handled = keyboard_keysym_press(keyboard,
+				syms[i], modifiers);
 			handled = handled || keysym_handled;
 		} else { // WLR_KEY_RELEASED
 			keyboard_keysym_release(keyboard, syms[i]);
 		}
 	}
 
+	return handled;
+}
+
+static void keyboard_key_notify(struct wl_listener *listener, void *data) {
+	struct wlr_event_keyboard_key *event = data;
+	struct roots_keyboard *keyboard = wl_container_of(listener, keyboard, key);
+
+	uint32_t keycode = event->keycode + 8;
+
+	bool handled = keyboard_keysyms_xkb(keyboard, keycode, event->state);
+
+	if (!handled)
+		handled |= keyboard_keysyms_simple(keyboard, keycode, event->state);
+
 	if (!handled) {
 		wlr_seat_set_keyboard(keyboard->input->wl_seat, keyboard->device);
 		wlr_seat_keyboard_notify_key(keyboard->input->wl_seat, event->time_msec,