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:/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.

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.

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

- not having lock can cause "block number list" to become corrupt => crash
- also may result in 2 threads receiving same block no => possble cause of
Bug #13987 Cluster: Loss of data nodes can cause high CPU usage from ndb_mgmd

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

into  mysql.com:/home/alexi/innodb/mysql-4.1-ss29

- invalidate ndb dict cache on cluster disconnect (ClusterMgr.cpp)
- add check for correct frm on external lock when table cache is found invalid

 Fix BUG#19542 "InnoDB doesn't increase the Handler_read_prev counter.
 

fixing names length. Got an issue when merged to 5.0, decided to fix starting from 4.1

mysqltest program should be really multithreaded to perform this
test with the embedded server. So this test disabled until we
redo mysqltest this way

this test just can't work in the embedded server

fixing a path to find charset by $MYSQL client. I believe the fix is done what should be
by default. 

into  mysql.com:/usr_rh9/home/elkin.rh9/MySQL/Merge/4.1

into  mysql.com:/usr_rh9/home/elkin.rh9/MySQL/Merge/4.1

  A pattern to generate binlog for DROPped temp table in close_temporary_tables
  was buggy: could not deal with a grave-accent-in-name table.

  The fix exploits `append_identifier()' for quoting and duplicating accents.

  Change mode to -rw-rw-r--
Ereport.pl, Ecreate.pl, Ecompare.pl:
  Change mode to -rwxrwxr--