allow only three failed change_user per connection.
successful change_user do NOT reset the counter

tests/mysql_client_test.c:
  make --error to work for --change_user errors

This bug could result in returning 0 for the expressions of the form 
<aggregate_function>(distinct field) when the system variable  
max_heap_table_size was set to a small enough number.
It happened because the method Unique::walk() did not support
the case when more than one pass was needed to merge the trees
of distinct values saved in an external file.

Backported a fix in grant_lowercase.test from mariadb 5.5.

MDEV-4029 SELECT on information_schema using a subquery locks up the information_schema table due to incorrect mutexes handling
  
Early evaluation of subqueries in the WHERE conditions on I_S.*_STATUS tables,
otherwise the subquery on this same table will try to acquire LOCK_status twice.

The original patch with the implementation of virtual columns
did not support INSERT DELAYED into tables with virtual columns.
This patch fixes the problem.

taking a change done to main 5.1 by Dmitri Lenev.

This is the original comment:

> committer: Dmitry Lenev <Dmitry.Lenev@oracle.com>
> branch nick: mysql-5.1-15954896
> timestamp: Wed 2012-12-05 19:26:56 +0400
> message:
>   Bug #15954896 "SP, MULTI-TABLE DELETE AND LONG ALIAS".

  Using too long table aliases in stored routines might
  have caused server crashes.

  Code in sp_head::merge_table_list() which is responsible
  for collecting information about tables used in stored
  routine was not aware of the fact that table alias might
  have arbitrary length. I.e. it assumed that table alias
  can't be longer than NAME_LEN bytes and allocated buffer
  for a key identifying table accordingly.

  This patch fixes the issue by ensuring that we use
  dynamically allocated buffer for table key when table
  alias is too long. By default stack based buffer is used
  in which NAME_LEN bytes are reserved for table alias.

The failure is caused by failing stat() call . C Runtime function stat() uses old struct with 32bit st_size member,
and since Visual Studio 2010 , it returns an error on st_size overflow (i.e on files larger than 4GB)

Fix replaces stat() by my_stat(), the later is backed by 64bit-able stat64().

Link feedback plugin with yassl libraries, if with-ssl=bundled is used, since mysqld does not export SSL symbols anymore.

Compile yassl and taocrypt using -fvisibility=hidden, when possible.  This prevent symbols from being exported.

Fix some problems in the TC_LOG_MMAP commit processing, which could
lead to assertions in some cases.

Problems are mostly reproducible in MariaDB 10.0 with asynchroneous
commit checkpoints, but most of the problems were present in earlier
versions also.

followup fixes for MySQL Bug #13889741: HANDLE_FATAL_SIGNAL IN _DB_ENTER_ | HANDLE_FATAL_SIGNAL IN STRNLEN

Take into account that length of strings passed down to this function can be up to FN_REFLEN+1 bytes. including terminating zero.
The overwrite was caused by incomplete fix to MySQL Bug # 44834

If triggers are used for an insert/update/delete statement than the values of
all virtual columns must be computed as any of them may be used by the triggers.

add a test case for MySQL Bug #13889741: HANDLE_FATAL_SIGNAL IN _DB_ENTER_ | HANDLE_FATAL_SIGNAL IN STRNLEN

Made information_schema_all_engines stable by adding "sorted_result".

Add missing DBUG_RETURNs, otherwise the debug-stack gets messed up,
and _db_enter_ and _db_exit_ will access data outside the current stack frame.