terminal: Ignore more modifier keys

Don't want these to leak into the terminal.
diff --git a/clients/terminal.c b/clients/terminal.c
index e0f54bd..457756d 100644
--- a/clients/terminal.c
+++ b/clients/terminal.c
@@ -2176,6 +2176,12 @@
 	case XKB_KEY_Control_R:
 	case XKB_KEY_Alt_L:
 	case XKB_KEY_Alt_R:
+	case XKB_KEY_Meta_L:
+	case XKB_KEY_Meta_R:
+	case XKB_KEY_Super_L:
+	case XKB_KEY_Super_R:
+	case XKB_KEY_Hyper_L:
+	case XKB_KEY_Hyper_R:
 		break;
 
 	case XKB_KEY_Insert: