patch 8.1.0487: no menus specifically for the terminal window

Problem:    No menus specifically for the terminal window.
Solution:   Add :tlmenu. (Yee Cheng Chin, closes #3439) Add a menu test.
diff --git a/src/popupmnu.c b/src/popupmnu.c
index 0f920dc..c481d4b 100644
--- a/src/popupmnu.c
+++ b/src/popupmnu.c
@@ -1176,7 +1176,7 @@
 	if ((mp->modes & mp->enabled & mode) && idx++ == pum_selected)
 	{
 	    vim_memset(&ea, 0, sizeof(ea));
-	    execute_menu(&ea, mp);
+	    execute_menu(&ea, mp, -1);
 	    break;
 	}
 }