revision-id: 673e253724979fd9fe43a4a22bd7e1b2c3a5269e
Author: Kristian Nielsen

Fix missing memory barrier in wait_for_commit.

The function wait_for_commit::wait_for_prior_commit() has a fast path where it
checks without locks if wakeup_subsequent_commits() has already been called.
This check was missing a memory barrier. The waitee thread does two writes to
variables `waitee' and `wakeup_error', and if the waiting thread sees the
first write it _must_ also see the second or incorrect behavior will occur.
This requires memory barriers between both the writes (release semantics) and
the reads (acquire semantics) of those two variables.

Other accesses to these variables are done under lock or where only one thread
will be accessing them, and can be done without barriers (relaxed semantics).

mysql_insert() first opens all affected tables (which implicitly
starts a transaction in InnoDB), then stat tables.
A failure to open a stat table caused open_tables() to abort
the current stmt transaction (trans_rollback_stmt()). So, from the
server point of view the following ha_write_row()-s happened outside
of a transactions, and the server didn't bother to commit them.

The server has a mechanism to prevent a transaction being
unexpectedly committed or rolled back in the middle of a statement -
if an operation takes place _in a sub-statement_ it cannot change
the transaction state. Operations on stat tables are exactly that -
they are not allowed to change a transaction state. Put them in
a sub-statement to make sure they don't.

- Use local variables table and share to simplify code
- Use sql_command_flags to detect what kind of command was used
- Added CF_DELETES_DATA to simplify detecton of delete commands
- Removed duplicate error in create_table_from_items().