Automatic merge from submit-queue
proxy/iptables: precompute svcPortName strings
With many services, the calls to svcPortName.String() show up as a
somewhat significant CPU user under syncProxyRules().
For whatever reason github repeatedly fails to upload the pprof with Firefox, so here's an example:
http://people.redhat.com/dcbw/kube-proxy-svcPortName-String.pdf