Add test cases for few edge cases which excercise the XML reporting from
libxml2 in anticipation of upcoming changes of behaviour.
'virschematest' must skip parsing of the broken file altogether so this
patch adds infrastructure to allow that.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>