[Dovecot] Disable APOP challenge in POP3 login greeting

[Timo Sirainen]

On Wed, 2010-08-18 at 13:11 -0700, Brad Davidson wrote:

> It looks like get_apop_challenge in 1.2 returns NULL if APOP isn't
> supported, which causes auth_client_ready to omit the banner... but I
> see no such check (in fact, no way for get_apop_challenge to return
> NULL) in 2.0, even though pop3_client_send_greeting tests for it.

Yeah, I removed the check because it wasn't anymore needed. I didn't
realize it was also there to check if APOP was disabled. Added back in
another way: http://hg.dovecot.org/dovecot-2.0/rev/eed1426f55a9