Pull up the following revisions (requested by tron in ticket #481):

doc/3RDPARTY 1.957
doc/CHANGES 1.1731
external/ibm-public/postfix/dist/HISTORY patch
external/ibm-public/postfix/dist/src/dns/dns_lookup.c patch
external/ibm-public/postfix/dist/src/global/mail_version.h patch
external/ibm-public/postfix/dist/src/local/biff_notify.c patch
external/ibm-public/postfix/dist/src/smtpd/smtpd_sasl_proto.c patch
external/ibm-public/postfix/dist/src/util/unix_pass_trigger.c patch

Update Postfix to version 2.8.12:
- The local(8) delivery agent's BIFF client leaked an unprivileged UDP
socket. Fix by Jaroslav Skarvada. This bug was introduced 19990127.
- The SMTP server did not reject the AUTH command while a MAIL FROM
transaction was in progress. Reported by Timo Sirainen.
This bug was introduced 20000314.
- The unused "pass" trigger client could close the wrong file
descriptors. This bug was introduced with Postfix 2.8.