patch 8.1.1274: after :unmenu can still execute the menu with :emenu

Problem:    After :unmenu can still execute the menu with :emenu.
Solution:   Do not execute a menu that was disabled for the specified mode.
diff --git a/src/menu.c b/src/menu.c
index 21d3e11..6e0c02e 100644
--- a/src/menu.c
+++ b/src/menu.c
@@ -2337,7 +2337,8 @@
     if (idx == -1 || eap == NULL)
 	idx = MENU_INDEX_NORMAL;
 
-    if (idx != MENU_INDEX_INVALID && menu->strings[idx] != NULL)
+    if (idx != MENU_INDEX_INVALID && menu->strings[idx] != NULL
+						 && (menu->modes & (1 << idx)))
     {
 	/* When executing a script or function execute the commands right now.
 	 * Also for the window toolbar.