Bug#20627 - INSERT DELAYED does not honour auto_increment_* variables

INSERT DELAYED ignored an explicitly set INSERT_ID and session
specific auto_increment_* variables.

The problem was that the inserts are done by a system thread,
which does not have access to the session variables of the user
thread.

On a proposal of Guilhem I fixed it so that the variables are
copied to the data structure for every delayed row. The system
thread sets its session variables from these values.

Only MyISAM tables locked with LOCK TABLES ... WRITE were affected.

A query that is optimized with index_merge doesn't reflect rows
inserted within LOCK TABLES.

MyISAM doesn't flush a state within LOCK TABLES. index_merge
optimization creates a copy of the handler, which thus gets
outdated MyISAM state.

New handler->clone() method is introduced to fix this problem.
For non-MyISAM storage engines it allocates a handler and opens
it with ha_open(). For MyISAM it additionally copies MyISAM state
pointer to cloned handler.

into  chilla.local:/home/mydev/mysql-5.0-bug14400

into  chilla.local:/home/mydev/mysql-4.1-bug14400

            "concurrent insert"
Additional fix for full keys and test case.

into  chilla.local:/home/mydev/mysql-4.1-bug14400

            subject of "concurrent insert"
Better fix by Monty: "The previous bug fix didn't work
when using partial keys."

into  may.pils.ru:/home/svoj/devel/mysql/BUG14770/mysql-5.0-engines

            columns
Fixed confusing warning.

Quoting INSERT section of the manual:
----
Inserting NULL into a column that has been declared NOT NULL. For
multiple-row INSERT statements or INSERT INTO ... SELECT statements, the
column is set to the implicit default value for the column data type. This
is 0 for numeric types, the empty string ('') for string types, and the
"zero" value for date and time types. INSERT INTO ... SELECT statements are
handled the same way as multiple-row inserts because the server does not
examine the result set from the SELECT to see whether it returns a single
row. (For a single-row INSERT, no warning occurs when NULL is inserted into
a NOT NULL column. Instead, the statement fails with an error.)
----
This is also true for LOAD DATA INFILE. For INSERT user can specify
DEFAULT keyword as a value to set column default. There is no similiar
feature available for LOAD DATA INFILE.

  "Test case 'csv' produces incorrect result on OpenBSD"
  mmapped pages were not being invalidated when writes occurred to the
  file vi a fd i/o operation. 
  Force explicit invalidation and not rely on implicit invalidation.

into  chilla.local:/home/mydev/mysql-5.0-bug20719

into  chilla.local:/home/mydev/mysql-5.0-bug20719

After merge fix

into  chilla.local:/home/mydev/mysql-5.0-bug20719

After merge fix

into  chilla.local:/home/mydev/mysql-5.0-bug20719

into  chilla.local:/home/mydev/mysql-4.1-bug20719

Added HA_NULL_IN_KEY to table flags to allow for nullable unique indexes
and added test to verify

ha_federated.h:
  BUG #15133 "unique index with nullable value not accepted in federated table"
  added HA_NULL_IN_KEY to table flags to allow for nullable unique indexes
federated.test:
  BUG #15133 "unique index with nullable value not accepted in federated table"
  New test to show that nullable unique indexes work
federated.result:
  BUG #15133 "unique index with nullable value not accepted in federated table"
  New results for new test

into  chilla.local:/home/mydev/mysql-4.1

into  chilla.local:/home/mydev/mysql-5.0

Fixed a possible problem with reading of dynamic records
when a write cache is active. The cache must be flushed
whenever a part of the file in the write cache is to be 
read.

Added a read optimization to _mi_read_dynamic_record().

No test case. This was a hypothetical but existing problem.

Post merge changes.

into  govinda.patg.net:/home/patg/mysql-build/mysql-5.0-bug18764.2

into  rama.(none):/home/jimw/my/mysql-5.0-17608

Removed logic in ha_federated::write_row, which checks field query ids in the
loop which builds the query to run on the remote server.

  The Federated storage engine used Field methods that had arbitrary limits on
  the amount of data they could process, which caused problems with data
  over that limit (4K). By removing those Field methods and just using
  features of the String class, we can avoid this problem.

into  dl145k.mysql.com:/data0/mkindahl/bk/mysql-5.0-rpl

into  rama.(none):/home/jimw/my/mysql-5.0-17766

 Changed the error reporting (and a crash) when inserting data into a
 MERGE table that has no underlying tables or no INSERT_METHOD specified
 by reporting that it is read-only.

into  bodhi.local:/opt/local/work/mysql-5.0-runtime-merge-41

into  chilla.local:/home/mydev/mysql-5.0-amerge

into  trift2.:/M50/mysql-5.0

into  dl145k.mysql.com:/data0/mkindahl/bk/MERGE/mysql-5.0-merge

into  bodhi.local:/opt/local/work/mysql-5.0-runtime-merge-41

into  trift2.:/M50/mysql-5.0