Log Message:
Update to 1.4.23.

Changelog:
Version 1.4.23:
- Fix SCRAM-SHA-1 authentication via libgsasl. Reported and analyzed by
  Steffen Lehmann for mpop.

Version 1.4.22:
- Update gnulib to 2010-12-23.
- Avoid different account selection behaviour in --pretend mode, and print more
  informational messages about account selection in --pretend and --debug mode.
  Suggested by Adam Spiers.
- Add a new passwordeval command and --passwordeval option, to set the password
  from the output of a command. Written by Martin Stenberg.
- A few documentation improvements, suggested by Andries E. Brouwer.