Fix cross compilation breakage

- happened becasue of two independent commits

Signed-off-by: Alessandro Boch <aboch@docker.com>

libnetwork/ipams/windowsipam/windowsipam.go

@@ -4,6 +4,7 @@ import (
 	"net"
 
 	log "github.com/Sirupsen/logrus"
+	"github.com/docker/libnetwork/discoverapi"
 	"github.com/docker/libnetwork/ipamapi"
 	"github.com/docker/libnetwork/types"
 )
@@ -80,3 +81,13 @@ func (a *allocator) ReleaseAddress(poolID string, address net.IP) error {
 	log.Debugf("ReleaseAddress(%s, %v)", poolID, address)
 	return nil
 }
+
+// DiscoverNew informs the allocator about a new global scope datastore
+func (a *allocator) DiscoverNew(dType discoverapi.DiscoveryType, data interface{}) error {
+	return nil
+}
+
+// DiscoverDelete is a notification of no interest for the allocator
+func (a *allocator) DiscoverDelete(dType discoverapi.DiscoveryType, data interface{}) error {
+	return nil
+}