ogleproxy: fix duplicate "Usage". flag.Usage already prints "Usage".

LGTM=r
R=r
https://golang.org/cl/128530043
diff --git a/cmd/ogleproxy/main.go b/cmd/ogleproxy/main.go
index 72967bc..5a53e41 100644
--- a/cmd/ogleproxy/main.go
+++ b/cmd/ogleproxy/main.go
@@ -25,7 +25,7 @@
 	log.SetPrefix("ogleproxy: ")
 	flag.Parse()
 	if *textFlag == "" {
-		fmt.Printf("OGLE BAD\nUsage")
+		fmt.Printf("OGLE BAD\n")
 		flag.Usage()
 		os.Exit(2)
 	}