misc/dashboard/builder: increase default command timeout

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6499127

misc/dashboard/builder/main.go

@@ -55,7 +55,7 @@ var (
 	failAll       = flag.Bool("fail", false, "fail all builds")
 	parallel      = flag.Bool("parallel", false, "Build multiple targets in parallel")
 	buildTimeout  = flag.Duration("buildTimeout", 60*time.Minute, "Maximum time to wait for builds and tests")
-	cmdTimeout    = flag.Duration("cmdTimeout", 2*time.Minute, "Maximum time to wait for an external command")
+	cmdTimeout    = flag.Duration("cmdTimeout", 5*time.Minute, "Maximum time to wait for an external command")
 	verbose       = flag.Bool("v", false, "verbose")
 )