all: run gofmt -s on source code

Per the description, the "-s" file issues slight simplifications to
the source code.

Change-Id: I77395d763f5eafb48653902dcedfa56b150b2d67
Reviewed-on: https://go-review.googlesource.com/80138
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

ssh/certs.go

@@ -343,7 +343,7 @@ func (c *CertChecker) CheckCert(principal string, cert *Certificate) error {
 		return fmt.Errorf("ssh: certicate serial %d revoked", cert.Serial)
 	}
 
-	for opt, _ := range cert.CriticalOptions {
+	for opt := range cert.CriticalOptions {
 		// sourceAddressCriticalOption will be enforced by
 		// serverAuthenticate
 		if opt == sourceAddressCriticalOption {

ssh/session.go

@@ -406,7 +406,7 @@ func (s *Session) Wait() error {
 		s.stdinPipeWriter.Close()
 	}
 	var copyError error
-	for _ = range s.copyFuncs {
+	for range s.copyFuncs {
 		if err := <-s.errors; err != nil && copyError == nil {
 			copyError = err
 		}

ssh/test/banner_test.go

@@ -8,7 +8,6 @@ package test
 
 import (
 	"testing"
-
 )
 
 func TestBannerCallbackAgainstOpenSSH(t *testing.T) {