Incremental patch part 2

Removing dead code and changing a note level message to a warning.

During start up some plugins are disabled by default. This caused an additional
warning level message to be emitted as a result of a previous bug patch. Since
there is risk of unnecessary confusion regarding the operation level of the server
the redundant information is removed.

This fixes the regression introduced in 5.1 that prevents 64 bit builds on Intel while still keeping the core2 hack operational so the cluster can build.

Remove a self assignment.
Rework a few constructs to avoid a potential overflow.

Based upon patch contributed by Michal Hrusecky

On 64-bits machines the calculation gets the wrong types and results
in very large numbers. Fixed by explicitly cast month to (int)

Failing to connect would release parts of the MYSQL struct.
We would then proceed to try again to connect without re-
initializing the struct.

We prevent the unwanted freeing of data we'll still need now.

Update the test case for BUG#44331 to fix the push build failure.

            results in server crash 
 
check_group_min_max_predicates() assumed the input condition 
item to be one of COND_ITEM, SUBSELECT_ITEM, or FUNC_ITEM. 
Since a condition of the form "field" is also a valid condition 
equivalent to "field <> 0", using such a condition in a query 
where the loose index scan was chosen resulted in a debug 
assertion failure. 
 
Fixed by handling conditions of the FIELD_ITEM type in 
check_group_min_max_predicates(). 

If an EVENT is created without the DEFINER clause set explicitly or with it set  
to CURRENT_USER, the master and slaves become inconsistent. This issue stems from 
the fact that in both cases, the DEFINER is set to the CURRENT_USER of the current 
thread. On the master, the CURRENT_USER is the mysqld's user, while on the slave,  
the CURRENT_USER is empty for the SQL Thread which is responsible for executing 
the statement.

To fix the problem, we do what follows. If the definer is not set explicitly,  
a DEFINER clause is added when writing the query into binlog; if 'CURRENT_USER' is 
used as the DEFINER, it is replaced with the value of the current user before 
writing to binlog.

with gcc 4.3.2
      
This patch fixes a number of GCC warnings about variables used
before initialized. A new macro UNINIT_VAR() is introduced for
use in the variable declaration, and LINT_INIT() usage will be
gradually deprecated. (A workaround is used for g++, pending a
patch for a g++ bug.)
      
GCC warnings for unused results (attribute warn_unused_result)
for a number of system calls (present at least in later
Ubuntus, where the usual void cast trick doesn't work) are
also fixed.

When a connection is dropped any remaining temporary table is also automatically
dropped and the SQL statement of this operation is written to the binary log in
order to drop such tables on the slave and keep the slave in sync. Specifically,
the current code base creates the following type of statement:
DROP /*!40005 TEMPORARY */ TABLE IF EXISTS `db`.`table`;

Unfortunately, appending the database to the table name in this manner circumvents
the replicate-rewrite-db option (and any options that check the current database).
To solve the issue, we started writing the statement to the binary as follows:
use `db`; DROP /*!40005 TEMPORARY */ TABLE IF EXISTS `table`;

Slave does not correctly handle "expected errors" leading to inconsistencies
between the mater and slave. Specifically, when a statement changes both
transactional and non-transactional tables, the transactional changes are
automatically rolled back on the master but the slave ignores the error and
does not roll them back thus leading to inconsistencies.
      
To fix the problem, we automatically roll back a statement that fails on
the slave but note that the transaction is not rolled back unless a "rollback"
command is in the relay log file.

  field references

This error requires a combination of factors : 
1. An "impossible where" in the outermost SELECT
2. An aggregate in the outermost SELECT
3. A correlated subquery with a WHERE clause that includes an outer 
field reference as a top level WHERE sargable predicate

When JOIN::optimize detects an "impossible WHERE" it will bail out
without doing the rest of the work and initializations. It will not
call make_join_statistics() as well.  And make_join_statistics fills 
in various structures for each table referenced.
When processing the result of the "impossible WHERE" the query must
send a single row of data if there are aggregate functions in it.
In this case the server marks all the aggregates as having received 
no rows and calls the relevant Item::val_xxx() method on the SELECT
list. However if this SELECT list happens to contain a correlated 
subquery this subquery is evaluated in a normal evaluation mode.
And if this correlated subquery has a reference to a field from the 
outermost "impossible where" SELECT the add_key_fields will mistakenly
consider the outer field reference as a "local" field reference when 
looking for sargable predicates.
But since the SELECT where the outer field reference refers to is not
completely initialized due to the "impossible WHERE" in this level
we'll get a NULL pointer reference.
Fixed by making a better condition for discovering if a field is "local"
to the SELECT level being processed. 
It's not enough to look for OUTER_REF_TABLE_BIT in this case since 
for outer references to constant tables the Item_field::used_tables() 
will return 0 regardless of whether the field reference is from the 
local SELECT or not.