gotest: generate gofmt-compliant code

R=r
CC=golang-dev
https://golang.org/cl/4400047

src/cmd/gotest/gotest.go

@@ -393,7 +393,7 @@ func writeTestmainGo() {
 	fmt.Fprintln(b)
 
 	// Benchmarks.
-	fmt.Fprintln(b, "var benchmarks = []testing.InternalBenchmark{")
+	fmt.Fprintf(b, "var benchmarks = []testing.InternalBenchmark{")
 	for _, f := range files {
 		for _, bm := range f.benchmarks {
 			fmt.Fprintf(b, "\t{\"%s.%s\", %s.%s},\n", f.pkg, bm, notMain(f.pkg), bm)