privilege".

Corrected addition of TRIGGER privilege by "mysql_fix_privilege_tables" script.
Problem with it should have been caught by system_mysql_db/system_mysql_db_fix
tests but they were disabled. Enabled them back.


mysql-test/r/system_mysql_db.result:
  Updated test results after addition of TRIGGER privilege.
mysql-test/t/disabled.def:
  Enabled back test system_mysql_db/system_mysql_db_fix tests.
scripts/mysql_fix_privilege_tables.sql:
  Corrected addition of TRIGGER privilege.