[source] opkg: mark as essential (FS#571)

[LEDE Commits]

jow pushed a commit to source.git, branch master:
https://git.lede-project.org/ebf846b00559a326d6ea5a1711d11335d89d1218

commit ebf846b00559a326d6ea5a1711d11335d89d1218
Author: Jo-Philipp Wich <jo at mein.io>
AuthorDate: Wed Mar 1 03:05:39 2017 +0100

    opkg: mark as essential (FS#571)
    
    Flag the opkg package as essential to avoid accidential uninstalls of it.
    
    Signed-off-by: Jo-Philipp Wich <jo at mein.io>
---
 package/system/opkg/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/package/system/opkg/Makefile b/package/system/opkg/Makefile
index f727f94..fbf87cb 100644
--- a/package/system/opkg/Makefile
+++ b/package/system/opkg/Makefile
@@ -12,6 +12,7 @@ include $(INCLUDE_DIR)/feeds.mk
 
 PKG_NAME:=opkg
 PKG_RELEASE:=1
+PKG_FLAGS:=essential
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL:=https://git.lede-project.org/project/opkg-lede.git