[package] do not set anything in DISABLE_IPV6 when set, let the package pick up the defaults

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@17077 3c298f89-4303-0410-b956-a3cf2f4a3e73

rules.mk

@@ -159,7 +159,7 @@ else
 endif
 
 ifeq ($(CONFIG_IPV6),y)
-  DISABLE_IPV6:=--enable-ipv6
+  DISABLE_IPV6:=
 else
   DISABLE_IPV6:=--disable-ipv6
 endif