allow ENGINE=FOOBAR in the discovering create table statement,
as long as the discovering engine is FOOBAR too

to be correct

  mysql-test/suite/engines/funcs/r/db_alter_collate_ascii.result
  mysql-test/suite/engines/funcs/r/db_alter_collate_utf8.result

MDEV-5217: Incorrect MyISAM event execution order causing incorrect parallel replication

In parallel replication, if transactions A,B group-commit together on the
master, we can execute them in parallel on a replication slave. But then, if
transaction C follows on the master, on the slave, we need to be sure that
both A and B have completed before starting on C to be sure to avoid
conflicts.

The necessary wait is implemented such that B waits for A to commit before it
commits itself (thus preserving commit order). And C waits for B to commit
before it itself can start executing. This way C does not start until both A
and B have completed.

The wait for B's commit on A happens inside the commit processing. However, in
the case of MyISAM with no binlog enabled on the slave, it appears that no
commit processing takes place (since MyISAM is non-transactional), and thus
the wait of B for A was not done. This allowed C to start before A, which can
lead to conflicts and incorrect replication.

Fixed by doing an extra wait for A at the end of B before signalling C.

MDEV-5217: Unlock of de-allocated mutex

There was a race in the code for wait_for_commit::wakeup().

Since the waiter does a dirty read of the waiting_for_commit
flag, it was possible for the waiter to complete and deallocate
the wait_for_commit object while the waitee was still running
inside wakeup(). This would cause the waitee to access invalid
memory.

Fixed by putting an extra lock/unlock in the destructor for
wait_for_commit, to ensure that waitee has finished with the
object before it is deallocated.

MDEV-5217: Incorrect event pos update leading to corruption of reading of events from relay log

The rli->event_relay_log_pos was sometimes undated incorrectly when using
parallel replication, especially around relay log rotates. This could cause
the SQL thread to seek into an invalid position in the relay log, resulting in
errors about invalid events or even random corruption in some cases.

MDEV-5217: Last_sql_error lost in parallel replication.

For some reason, the query execution code in log_event.cc call
rli->clear_error for each event (part of clear_all_errors()).
This causes a problem in parallel replication, where the
execution in one worker thread could clear the error set by
another thread, causing the SQL thread to stop but leaving no
error visible in SHOW SLAVE STATUS.

There seems to be no reason to clear the global error code
in Relay_log_info for each event execution, from code review
and from running the test suite. So remove this clearing of
the error code to make things work also in the parallel case.

MDEV-5217: SQL thread hangs during stop if error occurs in the middle of an event group

Normally, when we stop the slave SQL thread in parallel replication, we want
the worker threads to continue processing events until the end of the current
event group. But if we stop due to an error that prevents further events from
being queued, such as an error reading the relay log, no more events can be
queued for the workers, so they have to abort even if they are in the middle
of an event group. There was a bug that we would deadlock, the workers
waiting for more events to be queued for the event group, the SQL thread
stopped and waiting for the workers to complete their current event group
before exiting.

Fixed by now signalling from the SQL thread to all workers when it is about
to exit, and cleaning up in all workers when so signalled.

This patch fixes one of multiple problems reported in MDEV-5217.

increase the initial ibdata1 size, as explained in MySQL-5.6 revid:kevin.lewis@oracle.com-20120802192452-kmikiz990xzje18b

"
  A maximum size of 10 Mb works in 5.1 because the initial
  required size of ibdata1 was less than 10M.  But in 5.5, a
  change was made to allocate all 128 rollback segments at
  bootstrap.  Since then, the initial size has been 10M + the
  default autoextend size of 8M. 

  In 5.6, worklog 6216 changes the autoextend size from 8M to
  64M.  This changes the initial size of ibdata1 from 18M in
  5.5 and earlier releases of 5.6 to 74M in the current
  mysql-5.6 and mysql-trunk.  So this change is especially
  needed in 5.6.
"

12M is enough to avoid autoextending during bootstrap

MDEV-5080 Assertion `strcmp(share->unique_file_name,filename) || share->last_version' fails at /storage/myisam/mi_open.c:67

extend table names discovery (ha_discover_table_names() and Discovered_table_list) to return
or optionally filter out temporary tables ("#sql..."). SHOW commands and I_S tables
typically want temp table filtered out, while DROP DATABASE wants to see them too.

additonally, remove the supression for the warning "Invalid (old?) table or database name"
from mtr, and add it to .test files as needed (we need to test that this warning
does *not* happen in drop.test)

(broken in the revid:sergii@pisem.net-20130615170931-bn2h8j30vu5bfp0t)

use the same inconsistent priv_user@host pair for SET ROLE privilege checks,
just as check_access() does

Updated --help text to declare --slave-parallel-threads as an alpha feature

mysql-test/r/mysqld--help.result:
  Updated --help text
sql/slave.cc:
  Added missing trans_retries++ that caused rpl_deadlock_innodb.test to fail.
  This is safe as this part is never run in parallel.
sql/sql_base.cc:
  Fixed temporary table handling (part of merge)
sql/sys_vars.cc:
  Updated --help text to declare --slave-parallel-threads as an alpha feature

10.0 part of the task, fix system tables