Fix handling of XML-1.0 XML namespace declaration Usually 'xml' namespace for XML-1.0 declaration does not need to be carried but Mike Hommey raised the problem that the SVG XSD file fails to parse due to a mishandling. - SAX2.c: failure to create a namespace should not be interpreted as a memory allocation error - tree.c: document better xmlNewNs behaviour, and fix it in the case the 'xml' prefix is being used.