Fix for a bug with test failing with Classic.

into linux.site:/home/marty/MySQL/mysql-5.0

into mysql.com:/media/sda1/mysql/mysql-5.0-926

into mysql.com:/media/sda1/mysql/mysql-5.0-926

 implementation of AVG(DISTINCT) which utilizes the approach with Fields.
The patch implemented in October is portede to the up-to-date tree 
containing DECIMAL type.
Tests for AVG(DISTINCT) (although there is not much to test provided
that SUM(DISTINCT) works), cleanups for COUNT(DISTINCT) and GROUP_CONCAT()
will follow in another changeset.

  Correct web links
fil0fil.c:
  Correct (?) English grammar

  Add a settable session variable innodb_support_xa; setting it to 0 can save up to 10 % of CPU time and 150 bytes of space in each undo log
trx0trx.h, trx0undo.c, trx0trx.c, trx0roll.c:
  Enable XA if innodb_support_xa is not set to 0; make prepare to do log fsync's according to innodb_flush_log_at_trx_commit

  Correction after manual merge.

  Added a test case for bug #9017.
item_cmpfunc.h:
  A wrong not_null_tables method for Item_cond_xor
  caused a conversion of a left join into an inner join
  that was not valid.

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

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

into mysql.com:/home/jimw/my/mysql-4.1-clean

  row_sel_store_mysql_rec(): Remove unused variable "index".

into mysql.com:/M41/mysql-4.1

into mysql.com:/usr/home/ram/work/5.0.b9029

into mysql.com:/usr/home/ram/work/5.0.b9029

into mysql.com:/usr/home/ram/work/5.0

into here.mwagner.org:/Users/mwagner/work/bk/mysql-4.1

into here.mwagner.org:/Users/mwagner/work/bk/mysql-5.0

  Many changes to improve error handling, and fix problem of multiple packaging processes trampling each other (32 & 64bit at the same time)

into mysql.com:/home/psergey/mysql-5.0-bug8711

Item_func_equal::not_null_tables() always return 0.

adapt the Windows build files accordingly.

into hundin.mysql.fi:/home/marko/mysql-5.0

into mysql.com:/home/timka/mysql/src/5.0-dbg

instead of SYS_TABLES.MIX_LEN, because the latter was not
initialized to zero in old MySQL 3.23 releases. This will break
existing MySQL/InnoDB 5.0.3-bk databases for which
SHOW TABLE STATUS displays Row_format=Compact.

into hundin.mysql.fi:/home/marko/mysql-5.0

  Restore sensible values to REC_OFFS_NORMAL_SIZE and REC_OFFS_SMALL_SIZE.

into mysql.com:/home/dlenev/src/mysql-5.0-sp