issue an error if string has illegal characters

Bug#30982 CHAR(..USING..) can return a not-well-formed string
Bug#30986 Character set introducer followed by a HEX string can return bad result
check_well_formed_result moved to Item from Item_str_func
fixed Item_func_char::val_str for proper ucs symbols converting
added check for well formed strings for correct conversion of constants with underscore
charset

into  mysql.com:/home/gluh/MySQL/Merge/5.0-opt

added variables relay_log, relay_log_index, relay_log_info_file to init_vars[]
to make them visible within SHOW VARIABLES

removed now() call to make the test to be year independent

into  dl145s.mysql.com:/data0/mhansson/bug31160/my50-bug31160

into  dl145s.mysql.com:/data0/mhansson/bug31160/my50-bug31160

Even though it returns NULL, the MAKETIME function did not have this property set,
causing a failed assertion (designed to catch exactly this).
Fixed by setting the nullability property of MAKETIME().

into  linux-st28.site:/home/martin/mysql/src/bug30832-again-push/my50-bug30832-again

Completion of previous patch. Negative number were denied
as the second argument to NAME_CONST.

into  mysql.com:/home/hf/work/30286/my50-30286

into  dl145s.mysql.com:/data0/mhansson/bug30942/my50-bug30942

into  mysql.com:/home/hf/work/30286/my50-30286

into  mysql.com:/home/hf/work/30286/my41-30286

into  mysql.com:/home/hf/work/30286/my50-30286

into  mysql.com:/home/hf/work/30286/my41-30286

into  mysql.com:/home/hf/work/30286/my50-30286

into  mysql.com:/home/hf/work/30286/my50-30286

As the result of DOUBLE claculations can be bigger
than DBL_MAX constant we use in code, we shouldn't use this constatn
as a biggest possible value.
Particularly the rtree_pick_key function set 'min_area= DBL_MAX' relying
that any rtree_area_increase result will be less so we return valid
key. Though in rtree_area_increase function we calculate the area
of the rectangle, so the result can be 'inf' if the rectangle is
huge enough, which is bigger than DBL_MAX.

Code of the rtree_pick_key modified so we always return a valid key.

into  trift2.:/MySQL/M50/push-5.0

added check for hidden I_S tables for 'show columns|keys' commands

into  production.mysql.com:/usersnfs/jperkin/bk/bug-27692/5.0

were accidentally removed during a previous rototill of this
code.  Fixes bug#27692.
  
While it can be argued we should strive to provide a 'secure by
default' installation, this happens to be the setup currently
documented in the manual as the default, so defer changes that
improve security out of the box to a co-ordinated effort later
on.
  
For now, make a note about the test databases and anonymous user
in mysql_install_db and recommend that mysql_secure_installation
be ran for users wishing to remove these defaults.

[..re-commit of previously lost change..]

into  dl145s.mysql.com:/data0/mhansson/bug30942/my50-bug30942

The function str_to_date has a field to say whether it's invoked constant 
arguments. But this member was not initialized, causing the function to
think that it could use a cache of the format type when said cache was in 
fact not initialized.
Fixed by initializing the field to false.

end-of-line check missed in Gis_read_stream::get_next_word,
what can lead to crashes (expecially with NULL strings).

End-of-line check added

into  gleb.loc:/home/uchum/work/bk/5.0-opt

  Bug #31077: post-commit fix.

into  gleb.loc:/home/uchum/work/bk/5.0-opt

  Bug #31077: post-commit fix.

   Updated variable size arrays to use vector like Jonas did for 5.1 so that my build would not break

into  gleb.loc:/home/uchum/work/bk/5.0-opt

into  magare.gmz:/home/kgeorge/mysql/autopush/B28702-vg-5.0-opt

into  dl145s.mysql.com:/data0/mhansson/bug30832/my50-bug30832

into  moonbone.local:/work/31095-bug-5.0-opt-mysql

The Item_func_rollup_const class is used for wrapping constants to avoid
wrong result for ROLLUP queries with DISTINCT and a constant in the select
list. This class is also used to wrap up a NULL constant but its null_value
wasn't set accordingly. This led to a server crash.

Now the null_value of an object of the Item_func_rollup_const class is set
by its fix_length_and_dec member function.

mysqldump adds the "-- Dump completed on YYYY-MM-DD hh:mm:ss" string
to the end of output if the --comments switch is on.
The only way to suppress this line is to use --skip-comments/--compact
switch.

New switch has been added to the mysqldump client command line:
--dump-date.

For the compatibility with previous releases, by default the --dump-date
is on.
The --dump-date switch forces mysqldump to add date to the
"-- Dump completed on ..." string at the end of output.
The --skip-dump-date switch supresses the output of date string
and uses short form of that commentary: "-- Dump completed".
--skip-comments or --compact switches disable the whole commentary
as usual.