A wrapper around xmlXPathRegisterNs that will save us
from having to include xpathInternals.h everywhere
we want to use a custom namespace and open-coding
the strings already contained in virXMLNamespace.
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NJiri Denemark <jdenemar@redhat.com>