patches/openwrt/umdns: add patch to umdns to fix missing seccomp json list

patches/openwrt/to-upstream/0041-umdns-add-check-for-seccomp.patch

+From 89d15f4db60294cc9ce24556ddf3e370db01430d Mon Sep 17 00:00:00 2001
+From: Jan Pavlinec <jan.pavlinec@nic.cz>
+Date: Fri, 27 Nov 2020 14:49:43 +0100
+Subject: [PATCH] umdns: add check for seccomp list
+
+This should fix  an issue when user have a
+router with enabled seccomp and tries to
+run umdns package which was build with
+SDK with disabled seccomp support.
+
+Signed-off-by: Jan Pavlinec <jan.pavlinec@nic.cz>
+---
+ package/network/services/umdns/Makefile         | 2 +-
+ package/network/services/umdns/files/umdns.init | 2 +-
+ 2 files changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/package/network/services/umdns/Makefile b/package/network/services/umdns/Makefile
+index dc032af31b4e..41945ce0079a 100644
+--- a/package/network/services/umdns/Makefile
++++ b/package/network/services/umdns/Makefile
+@@ -8,7 +8,7 @@
+ include $(TOPDIR)/rules.mk
+ 
+ PKG_NAME:=umdns
+-PKG_RELEASE:=1
++PKG_RELEASE:=2
+ 
+ PKG_SOURCE_URL=$(PROJECT_GIT)/project/mdnsd.git
+ PKG_SOURCE_PROTO:=git
+diff --git a/package/network/services/umdns/files/umdns.init b/package/network/services/umdns/files/umdns.init
+index c0b8cedd79b5..1ae1cccb039c 100644
+--- a/package/network/services/umdns/files/umdns.init
++++ b/package/network/services/umdns/files/umdns.init
+@@ -33,7 +33,7 @@ start_service() {
+ 
+ 	procd_open_instance
+ 	procd_set_param command "$PROG"
+-	procd_set_param seccomp /etc/seccomp/umdns.json
++	[ -f /etc/seccomp/umdns.json ] && procd_set_param seccomp /etc/seccomp/umdns.json
+ 	procd_set_param respawn
+ 	procd_open_trigger
+ 	procd_add_config_trigger "config.change" "umdns" /etc/init.d/umdns reload