Post fix for bug#16377

into moonbone.local:/home/evgen/bk-trees/mysql-4.1-opt

into moonbone.local:/home/evgen/bk-trees/mysql-4.1-opt

into moonbone.local:/work/16377-bug-4.1-opt-mysql

can lead to a wrong result.

All date/time functions has the STRING result type thus their results are
compared as strings. The string date representation allows a user to skip 
some of leading zeros. This can lead to wrong comparison result if a date/time 
function result is compared to such a string constant.

The idea behind this bug fix is to compare results of date/time functions
and data/time constants as ints, because that date/time representation is 
more exact. To achieve this the agg_cmp_type() is changed to take in the
account that a date/time field or an date/time item should be compared 
as ints.

This bug fix is partially back ported from 5.0.

The agg_cmp_type() function now accepts THD as one of parameters. 
In addition, it now checks if a date/time field/function is present in the
list. If so, it tries to coerce all constants to INT to make date/time
comparison return correct result. The field for the constant coercion is
taken from the Item_field or constructed from the Item_func. In latter case
the constructed field will be freed after conversion of all constant items.
Otherwise the result is same as before - aggregated with help of the
item_cmp_type() function.

From the Item_func_between::fix_length_and_dec() function removed the part
which was converting date/time constants to int if possible. Now this is 
done by the agg_cmp_type() function.

The new function result_as_longlong() is added to the Item class. 
It indicates that the item is a date/time item and result of it can be
compared as int. Such items are date/time fields/functions.

Correct val_int() methods are implemented for classes Item_date_typecast, 
Item_func_makedate, Item_time_typecast, Item_datetime_typecast. All these
classes are derived from Item_str_func and Item_str_func::val_int() converts
its string value to int without regard to the date/time type of these items.

Arg_comparator::set_compare_func() and Arg_comparator::set_cmp_func()
functions are changed to substitute result type of an item with the INT_RESULT
if the item is a date/time item and another item is a constant. This is done
to get a correct result of comparisons like date_time_function() = string_constant.

into moonbone.local:/home/evgen/bk-trees/mysql-4.1-opt

into moonbone.local:/work/16716-bug-4.1-opt-mysql

into  rurik.mysql.com:/home/igor/mysql-4.1-opt

The bug report revealed two problems related to min/max optimization:
1. If the length of a constant key used in a SARGable condition for
for the MIN/MAX fields is greater than the length of the field an 
unwanted warning on key truncation is issued;
2. If MIN/MAX optimization is applied to a partial index, like INDEX(b(4))
than can lead to returning a wrong result set.

        3.23 regression test failure

The member SEL_ARG::min_flag was not initialized, 
due to which the condition for no GEOM_FLAG in function 
key_or did not choose "Range checked for each record" as 
the correct access method.

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. 

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.

The Item_func_concat::val_str() function tries to make as less re-allocations
as possible. This results in appending strings returned by 2nd and next
arguments to the string returned by 1st argument if the buffer for the first
argument has enough free space. A constant subselect is evaluated only once 
and its result is stored in an Item_cache_str. In the case when the first
argument of the concat() function is such a subselect Item_cache_str returns
the stored value and Item_func_concat::val_str() append values of other
arguments to it. But for the next row the value in the Item_cache_str isn't
restored because the subselect is a constant one and it isn't evaluated second
time. This results in appending string values of 2nd and next arguments to the 
result of the previous Item_func_concat::val_str() call.

The Item_func_concat::val_str() function now checks whether the first argument 
is a constant one and if so it doesn't append values of 2nd and next arguments
to the string value returned by it.

into  production.mysql.com:/usersnfs/rkalimullin/4.1.b18351

  Update NDB version as well

  Stepped up to 4.1.22

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

into  production.mysql.com:/usersnfs/rkalimullin/4.1.b18351

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

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

into  mysql.com:/usr/home/ram/work/4.1.b18536

into mysql.com:/home/hf/work/mysql-4.1.clean

  Always compile position independent

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

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

 - A segfault occured when the function 'kill_server' called 
   'my_sigset' with signal number 0. 'my_sigset' is a macro which
   uses 'sigaction' to install the signal handler with an invalid
   signal number will on most platforms return EINVAL but yields
   a segfauilt on IRIX 6.5
 - The server crash was detected by mysqld_safe and it was restarted although
   a shutdown was requested. 
 - Semantics of kill_server(0) is not known, leaving it intact

into  neptunus.(none):/home/msvensson/mysql/bug18818/my41-bug18818

into  production.mysql.com:/usersnfs/tulin/mysql-4.1

into  poseidon.ndb.mysql.com:/home/tomas/mysql-4.1-main

into  poseidon.ndb.mysql.com:/home/tomas/mysql-4.1-main

    ndb: ndb_waiter disconnect/reconnect on get status error

into  production.mysql.com:/usersnfs/tulin/mysql-4.1

into  mysql.com:/data0/mysqldev/my/mysql-4.1

fixing encoding example because of table names can not be in koi8r 
on some platforms.