dhcp: allow IPv6 to be turned on

Signed-off-by: Heiko Zuerker <smiley73@users.sourceforge.net>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/dhcp/dhcp.mk

@@ -13,8 +13,11 @@ DHCP_CONF_OPT = \
 	--with-cli-lease-file=/var/lib/dhcp/dhclient.leases \
 	--with-srv-pid-file=/var/run/dhcpd.pid \
 	--with-cli-pid-file=/var/run/dhclient.pid \
-	--with-relay-pid-file=/var/run/dhcrelay.pid \
-	--disable-dhcpv6
+	--with-relay-pid-file=/var/run/dhcrelay.pid
+
+ifneq ($(BR2_INET_IPV6),y)
+        DHCP_CONF_OPT += --disable-dhcpv6
+endif
 
 ifeq ($(BR2_PACKAGE_DHCP_SERVER),y)
 define DHCP_INSTALL_SERVER