yaz_log_xml_errors: use log level given
yaz_log_xml_errors: use log level given

Fix yaz_log_xml_errors to use the log_level given.. Instead of YLOG_WARN.

dcrossleyau/yaz,dcrossleyau/yaz,nla/yaz,dcrossleyau/yaz,nla/yaz,nla/yaz,nla/yaz