python-lxml: upgrade 3.2.5 -> 3.4.4

* Dropped backported python-lxml-3.2.5-fix-CVE-2014-3146.patch
* Modify DISTUTILS_INSTALL_ARGS to avoid errors in the step of do_install
  | ValueError: invalid literal for int() with base 10:
    '--should-not-have-used-/usr/bin/xml2-config'
  | ERROR: python setup.py install execution failed.

Signed-off-by: Li Xin <lixin.fnst@cn.fujitsu.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>