send-email: provide whitelist of SMTP AUTH mechanisms
When sending an e-mail, the client and server must agree on an
authentication mechanism. Some servers (due to misconfiguration
or a bug) deny valid credentials for certain mechanisms. In this
patch, a new option --smtp-auth and configuration entry smtpAuth
are introduced. If smtp_auth is defined, it works as a whitelist
of allowed mechanisms for authentication selected from the ones
supported by the installed SASL perl library.
Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>