Hide DSN option in Preferences when smtp_server is not used (#1490666)

CHANGELOG

@@ -23,6 +23,7 @@ CHANGELOG Roundcube Webmail
 - Fix bug in long recipients list parsing for cases where recipient name contained @-char (#1490653)
 - Plugin API: Added addressbook_export hook
 - Fix additional_message_headers plugin compatibility with Mail_Mime >= 1.9 (#1490657)
+- Hide DSN option in Preferences when smtp_server is not used (#1490666)
 
 RELEASE 1.2-beta
 ----------------

program/steps/settings/func.inc

@@ -749,7 +749,7 @@ function rcmail_user_prefs($current = null)
                 );
             }
 
-            if (!isset($no_override['dsn_default'])) {
+            if (!isset($no_override['dsn_default']) && $RCMAIL->config->get('smtp_server')) {
                 if (!$current) {
                     continue 2;
                 }