Fix bug in mtr_cases.pm script visible only when InnoDB isn't configured.

Occasionally, if both the partition_pruning
and partition_range tests are run sequentially
against the IBMDB2I engine, the partition_range
test will fail.

Compiler padding on a 64-bit build allowed
garbage data in the hash key used for
caching open iconv descriptors. As a
result, cached descriptors were not found,
and multiple duplicate iconv descriptors
were opened for a single character set.
Eventually, the maximum number of open
iconv descriptors was reached, and further
iconv_open() calls would fail, leading the
storage engine to report incorrectly that
the character set was not supported.

This patch widens the 16-bit members of the
hash key to 32 bits to eliminate compiler
padding. The entire length of the hash key
is now initialized correctly on both 32-bit
and 64-bit builds.

In order to better support the usage of
IBMDB2I tables from within RPG programs,
the storage engine should ensure that the
RCDFMT name is consistent and predictable
for DB2 tables.

This patch appends a "RCDFMT <name>"
clause to the CREATE TABLE statement
that is passed to DB2.  <name> is
generated from the original name of
the table itself. This ensures a
consistent and deterministic mapping
from the original table.

For the sake of simplicity only
the alpha-numeric characters are
preserved when generating the new
name, and these are upper-cased;
other characters are replaced with
an underscore (_). Following DB2
system identifier rules, the name
always begins with an alpha-character
and has a maximum of ten characters.
If no usable characters are found in
the table name, the name X is used.

  It turns out that this test case no longer fails with the discrepancy
  in numbers that was the original cause for disabling this test (and showed
  potential genuine issues with the query cache). Therefore
  this test is being enabled after some minor adjustment of error codes and
  messages.

Details:
1. Add missing "disconnect <session>"
2. Take care that the disconnects are finished when the test terminates
3. Replace error names by error numbers
4. Minor beautifying of script code

 
Field_time::get_time() did not initialize some members of 
MYSQL_TIME which led to valgrind warnings when those members 
were accessed in Protocol_simple::store_time(). 
 
It is unlikely that this bug could result in wrong data 
being returned, since Field_time::get_time() initializes the 
'day' member of MYSQL_TIME to 0, so the value of 'day' 
in Protocol_simple::store_time() would be 0 regardless 
of the values for 'year' and 'month'.

Remove a cast (which shouldn't have got here anyway)
which might lose significant bits beyond 4 GB RAM.

In UNION if we use last SELECT without braces and this
SELECT have ORDER BY clause, such clause belongs to
global UNION. It is parsed like last SELECT
part and used further as 'unit->global_parameters->order_list' value.
During DESCRIBE EXTENDED we call select_lex->print_order() for
last SELECT where order fields refer to tmp table 
which already freed. It leads to crash.
The fix is clean up global_parameters->order_list
instead of fake_select_lex->order_list.

  UNIX sockets need to be on a path shorter than 70 characters on some older platofrms.
  MTRv1 tries to fix this by moving the socket to the $TMPDIR, however this causes
  issues with certain tests on Windows.

  Fixed by not applying any hacks on Windows - Windows does not need them.

It is not possible to prevent the server from starting if a mandatory
built-in plugin fails to start. This can in some cases lead to data
corruption when the old table name space suddenly is used by a different
storage engine.

A boolean command line option in the form of --foobar is automatically
created for every existing plugin "foobar". By changing this command line
option from a boolean to a tristate { OFF, ON, FORCE } it is possible to
specify the plugin loading policy for each plugin.

The behavior is specified as follows:
   OFF   = Disable the plugin and start the server
   ON    = Enable the plugin and start the server even if an error occurrs
           during plugin initialization.
   FORCE = Enable the plugin but don't start the server if an error occurrs
           during plugin initialization.

UNIX sockets need to be on a path shorter than 70 characters on some older platofrms.
MTRv1 tries to fix this by moving the socket to the $TMPDIR, however this causes
issues with certain tests on Windows.

Fixed by not applying any hacks on Windows - Windows does not need them.

checking in a test case that will reproduce
the error on v5r4.