cmd/gomote: fix gomote dialing to the coordinator after recent cert changes

No more self-signed cert on https://farmer.golang.org, so don't do the custom
TLS dialing anymore. Just use the standard tls.Dial.

Updates golang/go#16442

Change-Id: I2e29cbde3294aaaa74c0e82150ffe985f3639209
Reviewed-on: https://go-review.googlesource.com/39750
Reviewed-by: Keith Randall <[email protected]>

Author: bradfitz

build.go

@@ -40,6 +40,11 @@ func (ci CoordinatorInstance) TLSHostPort() (string, error) {
 }
 
 func (ci CoordinatorInstance) TLSDialer() func(network, addr string) (net.Conn, error) {
+	if ci == "prod" {
+		// TODO(bradfitz): once the staging coordinator has a
+		// DNS name and LetsEncrypt, delete this whole method?
+		return nil // uses default http.Transport.DialTLS dialer
+	}
 	caPool := x509.NewCertPool()
 	tlsConf := &tls.Config{
 		ServerName:         "go", // fixed name; see build.go