Change log_flush_frequency to use -

Since we have the rename, we don't need our declaration to look like
glog's.

hack/verify-flags/excluded-flags.txt

@@ -9,7 +9,6 @@ gke_context
 host_port_endpoints
 kubecfg_file
 kube_master_url
-log_flush_frequency
 max_in_flight
 max_par
 new_file_0644

hack/verify-flags/known-flags.txt

@@ -125,6 +125,7 @@ kube-master
 label-columns
 last-release-pr
 legacy-userspace-proxy
+log-flush-frequency
 long-running-request-regexp
 low-diskspace-threshold-mb
 manifest-url

pkg/util/logs.go

@@ -25,8 +25,7 @@ import (
 	"github.com/spf13/pflag"
 )
 
-// Uses _ instead of - to better align with glog flags.
-var logFlushFreq = pflag.Duration("log_flush_frequency", 5*time.Second, "Maximum number of seconds between log flushes")
+var logFlushFreq = pflag.Duration("log-flush-frequency", 5*time.Second, "Maximum number of seconds between log flushes")
 
 // TODO(thockin): This is temporary until we agree on log dirs and put those into each cmd.
 func init() {