bug#3160: smtpmail request, support immediate starttls

[Chong Yidong]

> I can successfully use smtp.gmail.com:587 to send mail using
> "gnutls-cli" to establish the encrypted bridge.  With this server:
> smtpmail exchanges greetings, then sends a STARRTLS command, then
> delivers a SIGALRM signal to "gnutls-cli" to build the bridge; after
> this the ESMTP dialogue goes on.  Fine.
>
> With the server relay.poste.it:465 (please do not mailbomb it) the
> procedure does not work because it wants the bridge built immediately,
> without exchanging greetings.
>
> The solution should be a customisable variable that selects the
> current procedure or an immediate call to `starttls-negotiate'.

This is fixed by the introduction of smtpmail-stream-type (which can be
set to `starttls') in the bzr trunk, so I'm closing this bug.