Ticket #3860 Correctly display SMTP SSL TLS boxes

After using the "Test" button, $_POST['smtpssl'] and $_POST['smtptls'] was 'on' or null - this got blindly copied back into $pconfig[] and resulted in the state of the SSL/TLS/STARTTLS checkboxes not being redisplayed.
Fixed by setting $pconfig['smtpssl'] and $pconfig['smtptls'] using the code that was previously done only to set these in $config
This pull request fixes it in 2.1 branch.
I will make another pull request for master 2.2