zerotier: make sure the /var/lib exists

Signed-off-by: Moritz Warning <moritzwarning@web.de>

net/zerotier/files/etc/init.d/zerotier

@@ -39,6 +39,9 @@ start_instance() {
 			return
 		fi
 
+		# ensure that the symlink target exists
+		mkdir -p $(dirname $path)
+
 		ln -s $config_path $path
 	fi