xml.result, xml.test:
  Adding test case.
item_xmlfunc.cc:
  Adding a special function to handle "self" axis.
  Previously "child" and "self" were handled the same.


sql/item_xmlfunc.cc:
  Bug#16315 XML: extractvalue() handles self badly
  Adding a special function to handle "self" axis.
  Previously "child" and "self" were handled the same.
mysql-test/t/xml.test:
  Adding test case.
mysql-test/r/xml.result:
  Adding test case.