The Item::tmp_table_field_from_field_type() function creates Field_datetime
object instead of Field_timestamp object for timestamp field thus always
changing data type is a tmp table is used.

The Field_blob object constructor which is used in the 
Item::tmp_table_field_from_field_type() is always setting packlength field of
newly created blob to 4. This leads to changing fields data type for example
from the blob to the longblob if a temporary table is used.

The Item::make_string_field() function always converts Field_string objects 
to Field_varstring objects. This leads to changing data type from the 
char/binary to varchar/varbinary.

Added appropriate Field_timestamp object constructor for using in the 
Item::tmp_table_field_from_field_type() function.

Added Field_blob object constructor which sets pack length according to
max_length argument.

The Item::tmp_table_field_from_field_type() function now creates
Field_timestamp object for a timestamp field.

The Item_type_holder::display_length() now returns correct NULL length NULL
length. 

The Item::make_string_field() function now doesn't change Field_string to
Field_varstring in the case of Item_type_holder. 

The Item::tmp_table_field_from_field_type() function now uses the Field_blob
constructor which sets packlength according to max_length.

  After merge fix

into moonbone.local:/work/18360-bug-4.1-mysql-opt

The IN() function uses agg_cmp_type() to aggregate all types of its arguments
to find out some common type for comparisons. In this particular case the 
char() and the int was aggregated to double because char() can contain values
like '1.5'. But all strings which do not start from a digit are converted to
0. thus 'a' and 'z' become equal. 
This behaviour is reasonable when all function arguments are constants. But 
when there is a field or an expression this can lead to false comparisons. In
this case it makes more sense to coerce constants to the type of the field
argument.

The agg_cmp_type() function now aggregates types of constant and non-constant
items separately. If some non-constant items will be found then their
aggregated type will be returned. Thus after the aggregation constants will be
coerced to the aggregated type. 

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

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

into  devsrv-b.mysql.com:/users/msvensson/mysql-5.0

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

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

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

into  devsrv-b.mysql.com:/users/msvensson/mysql-5.0

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

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

In multi-table delete a table for delete can't be used for selecting in
subselects. Appropriate error was raised but wasn't checked which leads to a
crash at the execution phase.

The mysql_execute_command() now checks for errors before executing select
for multi-delete.

into  mysql.com:/home/emurphy/iggy/mysql-5.0

into  mysql.com:/home/kgeorge/mysql/5.0/clean

into  mysql.com:/home/kgeorge/mysql/5.0/B18681

into  mysql.com:/home/kgeorge/mysql/5.0/B18681

into  mysql.com:/home/kgeorge/mysql/5.0/B14875

When reading a view definition from a .frm file it was
throwing a SQL error if the DEFINER user is not defined.
Changed it to a warning to match the (documented) case
when a view with undefined DEFINER user is created.

The check for view security was lacking several points :
1. Check with the right set of permissions : for each table ref that
participates in a view there were the right credentials to use in it's
security_ctx member, but these weren't used for checking the credentials.
This makes hard enforcing the SQL SECURITY DEFINER|INVOKER property
consistently.
2. Because of the above the security checking for views was just ruled out
in explicit ways in several places.
3. The security was checked only for the columns of the tables that are
brought into the query from a view. So if there is no column reference
outside of the view definition it was not detecting the lack of access to
the tables in the view in SQL SECURITY INVOKER mode.

The fix below tries to fix the above 3 points.

into  mysql.com:/space/pekka/ndb/version/my50-bug14509

into  mysql.com:/space/pekka/ndb/version/my50-bug14509

into  mysql.com:/home/kgeorge/mysql/5.0/clean

into  mysql.com:/home/kgeorge/mysql/5.0/B18742-2

into  mysql.com:/home/kgeorge/mysql/5.0/B18742-2

into  mysql.com:/home/kgeorge/mysql/5.0/B19700

  
The unsigned flag in Item was not propagated through the single value subqueries.
This caused the result to be treated as signed.

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

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

Replaced COND_refresh with COND_global_read_lock becasue of a bug in NTPL threads when using different mutexes as arguments to pthread_cond_wait()
The original code caused a hang in FLUSH TABLES WITH READ LOCK in some circumstances because pthread_cond_broadcast() was not delivered to other threads.
This fixes:
Bug#16986: Deadlock condition with MyISAM tables
Bug#20048: FLUSH TABLES WITH READ LOCK causes a deadlock

into  april.(none):/home/svoj/devel/mysql/BUG17001/mysql-5.0