simplenews_count_spool() also counts pending entries which are not yet expired

This is inconsistent with simplenews_get_spool() and causes unecessary load for scripts which use the return value of that function to determine if there are mails to be sent and then call simplenews_mail_spool(), which will fail to load them an not send anything. This will then repeat until the pending entries expire or are sent.

Not sure if we need an option for this, because this will list pending mails as already sent in the overview. However, that is actually more or less true. They are not actually sent yet, but given that we add a stop newsletter action there, those pending entries will still be sent.

Patch coming soon.