cmd/derper: allow absent SNI when using manual certs and IP literal for hostname

Updates #11776

Change-Id: I81756415feb630da093833accc3074903ebd84a7
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/derper/derper_test.go

@@ -6,7 +6,6 @@ package main
 import (
 	"bytes"
 	"context"
-	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"strings"
@@ -138,5 +137,4 @@ func TestTemplate(t *testing.T) {
 	if !strings.Contains(str, "Debug info") {
 		t.Error("Output is missing debug info")
 	}
-	fmt.Println(buf.String())
 }