go.net/ipv4: remove arguments from example functions
go.net/ipv4: remove arguments from example functions

The testing packege expects that Example functions in each
package don't take any arguments. Will do so for the safety.

R=iant, dave, minux.ma, adg
CC=golang-dev
https://codereview.appspot.com/6591076

andrewzeneski/go.net,gigq/go.net,ssor/go.net,go-mirrors/go.net,polydawn-ports/go.net,fernandez14/go.net