Fix suspicious places in vendor

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

update-vendor.sh

@@ -44,7 +44,7 @@ clone git github.com/codegangsta/cli 1.1.0
 clone git github.com/coreos/go-systemd v2
 clone git github.com/godbus/dbus v2
 clone git github.com/Sirupsen/logrus v0.7.3
-clone git github.com/syndtr/gocapability 8e4cdcb
+clone git github.com/syndtr/gocapability 66ef2aa
 clone git github.com/golang/protobuf 655cdfa588ea
 
 # intentionally not vendoring Docker itself...  that'd be a circle :)

vendor/src/github.com/golang/protobuf/proto/all_test.go

@@ -1281,9 +1281,7 @@ func TestEnum(t *testing.T) {
 // We don't care what the value actually is, just as long as it doesn't crash.
 func TestPrintingNilEnumFields(t *testing.T) {
 	pb := new(GoEnum)
-	if fmt.Sprintf("%+v", pb) == "" {
-		t.Errorf("expected non-empty string")
-	}
+	fmt.Sprintf("%+v", pb)
 }
 
 // Verify that absent required fields cause Marshal/Unmarshal to return errors.