bMDEV-4906: When event apply fails, next SQL thread start errorneously commits the failing GTID to gtid_slave_pos

When a GTID event is executed, we remember the contained GTID position so that
when we have applied the entire event group we can commit it to
gtid_slave_pos.

However, if the event group fails to apply due to some error and the SQL
thread aborts, the code did not correctly clear the remembered GTID. Thus,
when SQL thread was restarted, the old GTID of the failing event group was
incorrectly updated to gtid_slave_pos when the initial rotate event was
executed, corrupting the GTID position.

mysql-test/r/func_set.result:
  merge

The function SELECT_LEX::mark_const_derived() must take into account that
in DELETE ... RETURNING join == NULL.

MDEV-4820: Empty master does not give error for slave GTID position that does not exist in the binlog

The main bug here was the following situation:

Suppose we set up a completely new master2 as an extra multi-master to an
existing slave that already has a different master1 for domain_id=0. When the
slave tries to connect to master2, master2 will not have anything that slave
requests in domain_id=0, but that is fine as master2 is supposedly meant to
serve eg. domain_id=1. (This is MDEV-4485).

But suppose that master2 then actually starts sending events from
domain_id=0. In this case, the fix for MDEV-4485 was incomplete, and the code
would fail to give the error that the position requested by the slave in
domain_id=0 was missing from the binlogs of master2. This could lead to lost
events or completely wrong replication.

The patch for this bug fixes this issue.

In addition, it cleans up the code a bit, getting rid of the fake_gtid_hash in
the code. And the error message when slave and master have diverged due to
alternate future is clarified, as requested in the bug description.

modified:
  mysql-test/r/dyncol.result
  mysql-test/r/type_time.result
  mysql-test/t/dyncol.test
  mysql-test/t/type_time.test
  mysys/ma_dyncol.c
  sql/item.cc
  sql/item_func.cc
pending merges:
  Alexander Barkov 2013-08-12 MDEV-4652 Wrong result for CONCAT(GREATEST(T...
    sanja@montyprogr... 2013-08-01 MDEV-4811 Assertion `offset < 0x1f' f...

set num_flag[] unconditionally, not under "if (column_names)"

http://ronaldbradford.com/blog/unexplained-trivial-mysql-behavior-2013-08-02/

pending merges:
  Alexander Barkov 2013-08-08 MDEV-4653 Wrong result for CONVERT_TZ(TIME('...

pending merges:
  Alexander Barkov 2013-08-08 MDEV-4512 Valgrind warnings in my_long10_to_...

Fixing a typo:  bit AND (&) was erroneously used instead of logical AND (&&) 

Includes all post-review fixes as well. 

partitioning enhancement for Bug#14521864

engine

MDEV-4812 Valgrind warnings (Invalid write) in dynamic_column_update_many on COLUMN_ADD

Fixed problem of working on wrong data (do not allow offset to out of string length).

- Modify the way Item_cond::fix_fields() and Item_cond::eval_not_null_tables() 
  calculate bitmap for Item_cond_or::not_null_tables():
  if they see a "... OR inexpensive_const_false_item OR ..." then the item can
  be ignored.
- Updated test results. There can be more warnings produced since parts of WHERE 
  are evaluated more times.

MDEV-4815 - allow multiple  mysql_server_init() / mysql_server_end() in the same process, for embedded library.

- Reset  static variables that are used to signal "init done"  for DBUG, in dbug_end()
- Set string server variables to NULL after memory for the value is freed - avoids double free()
- fix DBUG_ASSERTs that happened during reinitialization.

- Let _ma_record_pos() set SEARCH_PART_KEY when doing a search on
  a prefix of a [unique] key.  Otherwise, _ma_search_pos() would 
  find the first key equal to search key, and assume it is also 
  the last one, which will make a wrong estimate of key's position.

  A wrong key position may cause min_pos > max_pos and records_in_range()
  will return 0, which will make the optimizer think it's an impossible 
  range while in fact it is not.

(fix of http://bugs.mysql.com/bug.php?id=69623)

  
In the case of loose scan used as input for order by, end_send()
didn't detect correctly that a loose scan was used, and didn't copy
the non-aggregated fields from the temp table used for ORDER BY.
  
The fix uses the fact that the quick select used for sorting is
attached to JOIN::pre_sort_join_tab instead of JOIN::join_tab.

MDEV-4782: Valgrind warnings (Conditional jump or move depends on uninitialised value) with InnoDB, semijoin
- in sub_select(): don't call table->file->position() when reading the first record
  produced an error.

Backport the fix olav.sandstaa@sun.com-20101102184747-qfuntqwj021imy9r:
"Fix for Bug#52660 Perf. regr. using ICP for MyISAM on range queries on an index containing TEXT" 
(together with further fixes in that code) into MyISAM and Aria.