View check option clauses were ignored for updates of multi-table
views when the updates could not be performed on fly and the rows
to update had to be put into temporary tables first.



mysql-test/r/view.result:
  Added a test case for bug #25931.
mysql-test/t/view.test:
  Added a test case for bug #25931.
  Adjusted another existed test case to have the correct result.
sql/sql_update.cc:
  Fixed bug #25931.
  View check option clauses were ignored for updates of multi-table
  views when the updates could not be performed on fly and the rows
  to update had to be put into temporary tables first.
  Added the required check to multi_update::do_updates to fix the problem.