The problem was that in read only mode (read_only enabled),
the server would mistakenly deny data modification attempts
for temporary tables which belong to a transactional storage
engine (eg. InnoDB).

The solution is to allow transactional temporary tables to be
modified under read only mode. As a whole, the read only mode
does not apply to any kind of temporary table.


mysql-test/r/read_only_innodb.result:
  Add test case result for Bug#33669
mysql-test/t/read_only_innodb.test:
  Add test case for Bug#33669
sql/lock.cc:
  Rename mysql_lock_tables_check to lock_tables_check and make
  it static. Move locking related checks from get_lock_data to
  lock_tables_check. Allow write locks to temporary tables even
  under read-only.