[xml/sgml-pkgs] Bug#962464: Remove ICU dependency

[Nick Wellnhofer]

Package: libxml2

Bug #776254 requested that libxml2 uses ICU for character set conversion 
because of some unspecified issues with Chromium. This adds an otherwise 
useless, multi-megabyte dependency (larger than libxml2 itself). I propose to 
revert that change. This means that libxml2 will use iconv for character 
conversion as before.

I'm sure that the Chromium issues can be worked around in another way. I'm 
also disappointed that the Chromium developers never reached out to the 
libxml2 maintainers.