he has SELECT and INSERT privileges for table with primary key"
Now we set lex->duplicates= DUP_UPDATE right in parser if INSERT has
ON DUPLICATE KEY UPDATE clause, this simplifies insert_precheck()
function (this also fixes a bug) and some other code.
'SHOW GRANTS' syntax is added
'SHOW GRANTS FOR CURRENT_USER' syntax is added
'SHOW GRANTS FOR CURRENT_USER()' syntax is added
CURRENT_USER without parens in expressions(SELECT CURRENT_USER;)
