Extend enumerations with the values used for error handling to silence more

clang warnings.

server/commands/menu_commands.c

@@ -144,7 +144,7 @@ menu_add_item_func(Client *c, int argc, char **argv)
 
 	/* Find menuitem type */
 	itemtype = menuitem_typename_to_type(argv[3]);
-	if (itemtype == -1) {
+	if (itemtype == MENUITEM_INVALID) {
 		sock_send_error(c->sock, "Invalid menuitem type\n");
 		return 0;
 	}

server/menuitem.c

@@ -1555,7 +1555,7 @@ MenuItemType menuitem_typename_to_type(char *name)
 			}
 		}
 	}
-	return -1;
+	return MENUITEM_INVALID;
 }
 
 char *menuitem_type_to_typename(MenuItemType type)
@@ -1576,7 +1576,7 @@ MenuEventType menuitem_eventtypename_to_eventtype(char *name)
 			}
 		}
 	}
-	return -1;
+	return MENUEVENT_INVALID;
 }
 
 char *menuitem_eventtype_to_eventtypename(MenuEventType type)

server/menuitem.h

@@ -43,6 +43,7 @@
 
 /** These values are used in the function tables in menuitem.c ! */
 typedef enum MenuItemType {
+	MENUITEM_INVALID  = -1,
 	MENUITEM_MENU     = 0,
 	MENUITEM_ACTION   = 1,
 	MENUITEM_CHECKBOX = 2,
@@ -87,6 +88,7 @@ typedef enum MenuResult {
 
 /** Events caused by a menuitem */
 typedef enum MenuEventType {
+	MENUEVENT_INVALID = -1,	/**< Special value for error handling */
 	MENUEVENT_SELECT = 0,	/**< Item has been selected
 				 * (action chosen) */
 	MENUEVENT_UPDATE = 1,	/**< Item has been modified