cmd/derper: support custom TLS port when in manual mode (#3231)

Fixes #3232

Change-Id: I8dae5c01f9dfdfd6d45e34e4ca3534b642ae5c8e
Signed-off-by: oocococo <mercurial.lx@gmail.com>

cmd/derper/derper.go

@@ -141,7 +141,7 @@ func main() {
 
 	cfg := loadConfig()
 
-	serveTLS := tsweb.IsProd443(*addr)
+	serveTLS := tsweb.IsProd443(*addr) || *certMode == "manual"
 
 	s := derp.NewServer(cfg.PrivateKey, log.Printf)
 	s.SetVerifyClient(*verifyClients)