Fix bug #12947 : a consistent read could return inconsistent results; this bug was introduced in 5.0.5

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

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

into  sanja.is.com.ua:/home/bell/mysql/bk/work-bug3-5.0

- current_arena to stmt_arena: the thread may have more than one
'current' arenas: one for runtime data, and one for the parsed 
tree of a statement. Only one of them is active at any moment.
- set_item_arena -> set_query_arena, because Item_arena was renamed to 
Query_arena a while ago
- set_n_backup_item_arena -> set_n_backup_active_arena;
the active arena is the arena thd->mem_root and thd->free_list
are currently pointing at.
- restore_backup_item_arena -> restore_active_arena (with the same
rationale)
- change_arena_if_needed -> activate_stmt_arena_if_needed; this
method sets thd->stmt_arena active if it's not done yet.

into  sanja.is.com.ua:/home/bell/mysql/bk/work-bug3-5.0

into  eel.(none):/home/jonas/src/mysql-5.0-push

into  eel.(none):/home/jonas/src/mysql-5.0-push

into  eel.(none):/home/jonas/src/mysql-5.0-push

into  eel.(none):/home/jonas/src/mysql-5.0

into  mysql.com:/users/lthalmann/bk/mysql-5.0

  Always abort if node failure occured between startTransaction and commit
  (can later be improved by wl#2610)

  make sure not to cut log to early 
  (specificly not use LCP with maxGciStarted that has not yet completed)

into  neptunus.(none):/home/msvensson/mysql/mysql-4.1

into  neptunus.(none):/home/msvensson/mysql/mysql-5.0

into  mysql.com:/users/lthalmann/bk/mysql-5.0

into  mysql.com:/usr/home/bar/mysql-4.1.b12363

into  sanja.is.com.ua:/home/bell/mysql/bk/work-bug3-5.0

into  sanja.is.com.ua:/home/bell/mysql/bk/work-bug3-5.0

into  neptunus.(none):/home/msvensson/mysql/mysql-5.0

into  mysql.com:/usr/home/bar/mysql-4.1.b12363

into  mysql.com:/usr/home/bar/mysql-5.0

  Fix crash reported in bug 12849.
  It doesn't fix the whole problem though.
  Let Pem fix it later.

into  mysql.com:/users/lthalmann/bk/mysql-4.1-bug12542

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

and GRANT in multi-threaded environment" into 5.0 tree.

into  sanja.is.com.ua:/home/bell/mysql/bk/work-bug3-5.0

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

into  neptunus.(none):/home/msvensson/mysql/mysql-4.1