[xml] [PATCH] Added Python 3 subpackage to libxml2

[Tomas Radej <tradej redhat com>]

Hi, all.

I am a Fedora contributor and one of the people who work on the 
Python-3-as-default Change staged for Fedora 22 [1]. A critical part of 
this effort is having a package with Python 3 bindings for libxml2.

For this reason, I have created this patch that adds the libxml2-python3 
subpackage [2] while keeping all other parts of the original packaging 
intact. I would like to ask you to include this patch in libxml2 sources 
or articulate objections to it so that I can address them.

A few clarifications:
* The libxml2-python package needs to stay, there are a lot of programs 
depending on it, and we don't have the capacity to convert them too.
* The `%make clean` part was proposed by, and discussed with, Daniel 
Veillard, and I believe it provides the intended results.

Thank you,

Tomas Radej

[1] https://fedoraproject.org/wiki/Changes/Python_3_as_Default
[2] http://paste.fedoraproject.org/174978/27615714/raw/