user to update with 'SET PASSWORD = ...'. (Bug #12302)


mysql-test/r/grant2.result:
  Add new results
mysql-test/t/grant2.test:
  Add new tests
sql/set_var.cc:
  Pass priv_host into check_change_password().
sql/sql_acl.cc:
  Add exact flag for find_acl_user, so we can specify that we want
  an exact match on the hostname.