keepalived: add script security param to fix warning

Openwrt is a single user system. So keepalived is runnig as root.
If we add the config options `script_user root` and
`enabled_script_security' the following warnings are gone.

> local1.info Keepalived_vrrp[5382]: SECURITY VIOLATION - scripts are
being executed but script_security not enabled.

Signed-off-by: Florian Eckert <fe@dev.tdt.de>
(cherry picked from commit 1b1ba71063)

net/keepalived/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=keepalived
 PKG_VERSION:=2.0.18
-PKG_RELEASE:=3
+PKG_RELEASE:=4
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://www.keepalived.org/software

net/keepalived/files/keepalived.init

@@ -104,6 +104,9 @@ global_defs() {
 	config_get_bool linkbeat_use_polling "$1" linkbeat_use_polling 0
 	[ "$linkbeat_use_polling" -gt 0 ] && printf 'linkbeat_use_polling\n\n' >> "$KEEPALIVED_CONF"
 
+	printf '%bscript_user root\n' "${INDENT_1}" >> "$KEEPALIVED_CONF"
+	printf '%benabled_script_security\n' "${INDENT_1}" >> "$KEEPALIVED_CONF"
+
 	config_get notification_email "$1" notification_email
 	print_list_indent notification_email