on packed MyISAM tables

When fixing the indexes with "myisamchk -rq" after compressing
the table with "myisampack", an optionally supplied extension
".MYI" of the index file was not detected. The extension was
appended unconditionally. The result was ".MYI.MYI".

Now an extension is no longer appended if present already.
Thanks to David Shrewsbury for providing this patch.

Another problem was a misplaced parenthesis. We did never unpack
the file name ("~/..") and always returned a real path.

No test case. This is manually tested with the utilities
"myisampack" and "myisamchk".

into  mysql.com:/home/svoj/devel/mysql/BUG26238/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG26238/mysql-5.1-engines

INSERT DELAYED inserts garbage for BIT columns.

When delayed thread clones TABLE object, it didn't adjusted bit_ptr
to newly created record (though it correctly adjusts ptr and null_ptr).

This is fixed by correctly adjusting bit_ptr when performing a clone.
With this fix BIT values are stored correctly by INSERT DELAYED.

Extending varchar column length with ALTER TABLE may result in unusable
memory table.

The problem is that we use fast ALTER TABLE in this case, which is not
supported by now.

This is fixed by refusing fast ALTER TABLE when extending varchar column.
In other words force copy of a table during ALTER TABLE.

Affects MEMORY tables in 5.1 only.

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt

into  mysql.com:/home/psergey/mysql-5.1-bug26117

Before the fix: 
  ha_partition objects had ha_partition::m_part_info==NULL and that caused
  crash
After: 
- The new ha_partition::clone() function makes the clones use parent's
  m_part_info value.
- The parent ha_partition object remains responsible for deallocation of
  m_part_info.

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt

into  mysql.com:/home/gluh/MySQL/Merge/5.0-opt

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt

into  ymer.(none):/tmp/mysql-5.1

  Post fix for bug#23800.

  Post fix for bug#23800.
  Copy the table name of an Item_outer_ref to the conventional memory.

into  moonbone.local:/mnt/gentoo64/work/23800-bug1-5.0-opt-mysql

  Post fix for bug#23800.
  The Item_field constructor now increases the select_n_where_fields counter.
sql_yacc.yy:
  Post fix for bug#23800.
  Take into account fields that might be added by subselects.
sql_lex.h:
  Post fix for bug#23800.
  Added the select_n_where_fields variable to the st_select_lex class.
sql_lex.cc:
  Post fix for bug#23800.
  Initialization of the select_n_where_fields variable.

into  mysql.com:/home/my/mysql-5.1

Fixed compile-pentium64 scripts
Fixed wrong estimate of update_with_key_prefix in sql-bench
Merge bk-internal.mysql.com:/home/bk/mysql-5.1 into mysql.com:/home/my/mysql-5.1
Fixed unsafe define of uint4korr()
Fixed that --extern works with mysql-test-run.pl
Small trivial cleanups
This also fixes a bug in counting number of rows that are updated when we have many simultanous queries
Move all connection handling and command exectuion main loop from sql_parse.cc to sql_connection.cc
Split handle_one_connection() into reusable sub functions.
Split create_new_thread() into reusable sub functions.
Added thread_scheduler; Preliminary interface code for future thread_handling code.

Use 'my_thread_id' for internal thread id's
Make thr_alarm_kill() to depend on thread_id instead of thread
Make thr_abort_locks_for_thread() depend on thread_id instead of thread
In store_globals(), set my_thread_var->id to be thd->thread_id.
Use my_thread_var->id as basis for my_thread_name()
The above changes makes the connection we have between THD and threads more soft.

Added a lot of DBUG_PRINT() and DBUG_ASSERT() functions
Fixed compiler warnings
Fixed core dumps when running with --debug
Removed setting of signal masks (was never used)
Made event code call pthread_exit() (portability fix)
Fixed that event code doesn't call DBUG_xxx functions before my_thread_init() is called.
Made handling of thread_id and thd->variables.pseudo_thread_id uniform.
Removed one common 'not freed memory' warning from mysqltest
Fixed a couple of usage of not initialized warnings (unlikely cases)
Suppress compiler warnings from bdb and (for the moment) warnings from ndb

into  mysql.com:/home/my/mysql-5.0

into  mysql.com:/home/my/mysql-5.0

into  mysql.com:/home/my/mysql-5.0

Suppress compiler warnings from bdb and (for the moment) warnings from ndb

into  chilla.local:/home/mydev/mysql-5.1-bug25460

into  mysql.com:/home/my/mysql-5.0

Fixed a couple of usage of not initialized warnings (unlikely cases)

into  dl145s.mysql.com:/users/mhansson/mysql/autopush/5.0o-bug24010