luci-app-mosdns: fix DNS leak option does not work

* busybox sed does not support regular expression.

luci-app-mosdns/Makefile

@@ -1,7 +1,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=luci-app-mosdns
-PKG_VERSION:=1.5.12
+PKG_VERSION:=1.5.13
 PKG_RELEASE:=1
 
 LUCI_TITLE:=LuCI Support for mosdns

luci-app-mosdns/root/etc/init.d/mosdns

@@ -123,7 +123,11 @@ init_yaml() {
         sed -i "/ecs_remote/d;" $CONF
     fi
     # DNS Leak
-    [ $dns_leak -eq 1 ] && sed -i "0,/primary: query_is_non_local_ip/s/primary: query_is_non_local_ip/primary: forward_remote_upstream/" $CONF
+    if [ $dns_leak -eq 1 ]; then
+        sed -i "s/primary: UNDEFINED/primary: forward_remote_upstream/g" $CONF
+    else
+        sed -i "s/primary: UNDEFINED/primary: query_is_non_local_ip/g" $CONF
+    fi
     # Cloudflare IP
     if [ $cloudflare -eq 1 ]; then
         cloudflare_ip=$(sh $MOSDNS_SCRIPT cloudflare)

luci-app-mosdns/root/usr/share/mosdns/default.yaml

@@ -153,7 +153,7 @@ plugins:
   - tag: fallback
     type: fallback
     args:
-      primary: query_is_non_local_ip
+      primary: UNDEFINED
       secondary: forward_remote_upstream
       threshold: 500
       always_standby: true