CREATE/DROP TEMPORARY TABLE are not safe to optimistically replicate in
parallel with other transactions, so they need to be marked as "ddl" in the
binlog.

This was already done for stand-alone CREATE/DROP TEMPORARY. But temporary
tables can also be created and dropped inside a BEGIN...END transaction, and
such transactions were not marked as ddl. Nor was the DROP TEMPORARY TABLE
statement emitted implicitly when a client connection is closed.

So this patch adds such ddl mark for the missing cases.

The difference to Kristian's original patch is mainly a fix in
mysql_trans_commit_alter_copy_data() to remember the unsafe_rollback_flags
over the temporary commit.