[source] ar71xx/images/senao: fix reproducible issue using tar

[LEDE Commits]

lynxis pushed a commit to source.git, branch master:
https://git.lede-project.org/d98cafc7b6b06618ecc774efbb862b5e18b08831

commit d98cafc7b6b06618ecc774efbb862b5e18b08831
Author: Alexander Couzens <lynxis at fe80.eu>
AuthorDate: Sat Jun 24 18:33:52 2017 +0200

    ar71xx/images/senao: fix reproducible issue using tar
    
    Use deterministic sorting
    Use numeric owner/group
    Set uid/gid to 0
    
    Signed-off-by: Alexander Couzens <lynxis at fe80.eu>
---
 target/linux/ar71xx/image/senao.mk | 1 +
 1 file changed, 1 insertion(+)

diff --git a/target/linux/ar71xx/image/senao.mk b/target/linux/ar71xx/image/senao.mk
index 0c56aa4..57e3610 100644
--- a/target/linux/ar71xx/image/senao.mk
+++ b/target/linux/ar71xx/image/senao.mk
@@ -9,6 +9,7 @@ define Build/senao-factory-image
 	$(CP) $(rootfs) $@.senao/openwrt-senao-$(board)-root.squashfs
 
 	$(TAR) -c \
+		--numeric-owner --owner=0 --group=0 --sort=name \
 		$(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)") \
 		-C $@.senao . | gzip -9nc > $@