mysql-test/r/xml.result:
  - Adding test case
  - Fixing error message
mysql-test/t/xml.test:
  Adding test case
sql/item_xmlfunc.cc:
  For grammar rules with loops like:
  
    AdditiveExpr ::= MultiplicativeExpr ('+' MultiplicativeExpr)*
  
  If we scanned scanned '+' and then met an error when parsing
  MultiplicativeExpr, then we should fully stop parsing - without
  trying to apply any other rules.
  
  Fix: add "error" member into MY_XPATH structure,
  and make my_xpath_parse_term() never return success
  as soon as error set.
strings/xml.c:
  Adding my_xml_ctype map for flags, indicating
  whether a character is a space character, is a
  valid identifier start character, is a valid
  identifier body character. Using this map to
  properly scan identifiers. Also, using this map
  to scan spaces faster (instead of strchr).