keep /etc/group over reflash as well

SVN-Revision: 11919

package/base-files/files/sbin/sysupgrade

@@ -44,7 +44,7 @@ EOF
 
 add_uci_conffiles() {
 	local file="$1"
-	find /etc/config /etc/passwd /etc/dropbear /etc/firewall.* > "$file"
+	find /etc/config /etc/passwd /etc/group /etc/dropbear /etc/firewall.* > "$file"
 	return 0
 }