table immediately after

The problem was that rows inserted in a table by one connection was
not immediately visible if another connection queried the table,
even if the insert had committed.

The reason for the problem was that the server sent a status reply
to the client before it actually did the commit. Therefore it was
possible to get an OK from the server before the changes were made
permanent and visible to other connections.

This patch fixes the problem by not sending status messages to the
server until any changes made have been committed. No test case added
as reproducing the error requires very specific timing betweeen the
server and two or more clients.

This patch also fixes the following (duplicate) bugs:
Bug #29334 pseudo-finished SHOW GLOBAL STATUS
Bug #36618 myisam insert not immediately visible to select from another client
Bug #45864 insert on one connection, immediate query on another produces no result
Bug #51329 Inserts from one connection not immediately visible in second
           connection
Bug #41516 Assertion fails when error returned from
           handler::external_lock(thd, F_UNLCK)