dhcp: add config option for delayed-ack feature of dhcp server

This patch creates a config option for the ISC DHCP server to allow passing
--enable-delayed-ack to its configure script.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/dhcp/Config.in

@@ -13,6 +13,11 @@ config BR2_PACKAGE_DHCP_SERVER
 	help
 	  DHCP server from the ISC DHCP distribution.
 
+config BR2_PACKAGE_DHCP_SERVER_DELAYED_ACK
+	bool "Enable delayed ACK feature"
+	depends on BR2_PACKAGE_DHCP_SERVER
+	help
+	  Enable delayed ACK feature in the ISC DHCP server.
 
 config BR2_PACKAGE_DHCP_RELAY
 	bool "dhcp relay"

package/dhcp/dhcp.mk

@@ -17,6 +17,10 @@ DHCP_CONF_OPT = \
 	--with-cli-pid-file=/var/run/dhclient.pid \
 	--with-relay-pid-file=/var/run/dhcrelay.pid
 
+ifeq ($(BR2_PACKAGE_DHCP_SERVER_DELAYED_ACK),y)
+        DHCP_CONF_OPT += --enable-delayed-ack
+endif
+
 ifneq ($(BR2_INET_IPV6),y)
         DHCP_CONF_OPT += --disable-dhcpv6
 endif