go.tools/cmd/eg: Use Print, not Printf, to print Help string.

Fixes golang/go#7861

LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/95770043

cmd/eg/eg.go

@@ -42,7 +42,7 @@ func doMain() error {
 	args := flag.Args()
 
 	if *helpFlag {
-		fmt.Fprintf(os.Stderr, eg.Help)
+		fmt.Fprint(os.Stderr, eg.Help)
 		os.Exit(2)
 	}