Allow headless svc without ports to have endpoints

As cited in
https://github.com/kubernetes/dns/issues/174 - this is documented to
work, and I don't see why it shouldn't work.  We allowed the definition
of headless services without ports, but apparently nobody tested it very
well.

Manually tested clusterIP services with no ports - validation error.

Manually tested services with negative ports - validation error.

New tests failed, output inspected and verified.  Now pass.

pkg/controller/endpoint/endpoints_controller.go

@@ -472,9 +472,9 @@ func (e *EndpointController) syncService(key string) error {
 				totalReadyEps = totalReadyEps + readyEps
 				totalNotReadyEps = totalNotReadyEps + notReadyEps
 			}
-			subsets = endpoints.RepackSubsets(subsets)
 		}
 	}
+	subsets = endpoints.RepackSubsets(subsets)
 
 	// See if there's actually an update here.
 	currentEndpoints, err := e.endpointsLister.Endpoints(service.Namespace).Get(service.Name)