Log Message:
Update pear_Net-Sieve to 1.2.0.
Based on PR#43124 by Wen Heping.

Changes since version 1.2.0b1:
* Fix DIGEST-MD5 authentication (Aleksander Machniak, Bug #17285).
* Don't try to call dl() if mbstring extension isn't loaded (Bug #17038).
Changes since version 1.1.7:
* Added support for adding a custom debug handler (Aleksander Machniak, Request \ 
#16681).
* Fix breakage with certain locales, especially Turkish.
* Fix reading authentication responses without literals (Bug #16647).
* Code cleanup.