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.


mysql-test/r/grant2.result:
  Added test for bug #6173 "One can circumvent missing UPDATE privilege if
  he has SELECT and INSERT privileges for table with primary key"
mysql-test/t/grant2.test:
  Added test for bug #6173 "One can circumvent missing UPDATE privilege if
  he has SELECT and INSERT privileges for table with primary key"
sql/mysql_priv.h:
  insert_precheck() don't need "update" parameter any longer since
  now we set lex->duplicates to DUP_UPDATE if INSERT has ON DUPLICATE
  KEY UPDATE clause.
sql/sql_parse.cc:
  insert_precheck() don't need "update" parameter any longer since
  now we set lex->duplicates to DUP_UPDATE if INSERT has ON DUPLICATE
  KEY UPDATE clause, so it can determine whenever it is needed to
  require UPDATE_ACL by itself. Also calling of mysql_insert() is
  simplified.
sql/sql_prepare.cc:
  insert_precheck() don't need "update" parameter any longer since
  now we set lex->duplicates to DUP_UPDATE if INSERT has ON DUPLICATE
  KEY UPDATE clause, so it can determine whenever it is needed to
  require UPDATE_ACL by itself. Also calling of mysql_insert() is
  simplified.
sql/sql_yacc.yy:
  It is better to set Lex->duplicates= DUP_UPDATE right in parser if we
  have INSERT with ON DUPLICATE KEY UPDATE clause, rather doing this later.