Compiling with debug and assigning an invalid directory to --slave-load-tmpdir
was crashing the slave due to the following assertion DBUG_ASSERT(! is_set() ||
can_overwrite_status). This assertion assumes that a thread can change its
state once (i.e. ok,error, etc) before aborting, cleaning/resuming or completing
its execution unless the overwrite flag (i.e. can_overwrite_status) is true.

The Append_block_log_event::do_apply_event which is responsible for creating
temporary file(s) was not cleaning the thread state. Thus a failure while
trying to create a file in an invalid temporary directory was causing the crash.

To fix the problem we check if the temporary directory is valid before starting
the SQL Thread and reset the thread state before creating a file in
Append_block_log_event::do_apply_event.

      
The copy of the original arguments of a aggregate function was not
initialized until after fix_fields().
Sometimes (e.g. when there's an error processing the statement)
the print() can be called with no corresponding fix_fields() call.
      
Fixed by adding a check if the Item is fixed before using the arguments
copy.

mysql-test/r/explain.result:
  Bug #43354: test case
mysql-test/t/explain.test:
  Bug #43354: test case
sql/item_sum.cc:
  Bug #43354: use the argument list copy only if it's initialized

The method to purge binary log files produces different results in some platforms.
The reason is that the purge time is calculated based on table modified time and
that can't guarantee to purge master-bin.000002 in all platforms.(eg. windows)

Use a new way that sets the time to purge binlog file 1 second after the last modified time of master-bin.000002.
That can be sure that the file is always deleted in any platform.

mysql-test/suite/rpl/r/rpl_rotate_logs.result:
  Test result
mysql-test/suite/rpl/t/rpl_rotate_logs.test:
  Change 'purge time' 1 sencond after the last modified time of master-bin.000002.

Took the Xfree implementation (based on the same rewrite as the NDB one)
and added it instead of the current implementation.
Added a macro to make the calls to MD5 more streamlined. 

client/mysqlmanager-pwgen.c:
  Bug #42434: changed to call the macro
include/my_md5.h:
  Bug #42434: use the Xfree implementation
mysys/md5.c:
  Bug #42434: use the Xfree implementation
sql/item_strfunc.cc:
  Bug #42434: changed to call the macro
sql/table.cc:
  Bug #42434: changed to call the macro
tools/mysqlmanager.c:
  Bug #42434: changed to call the macro

Changes are due to changes in precision.
Re-record of .result files to account for new server precision.

test-fixes for 32-bit

mysql-test/t/variables.test:
  Test for 10351 ("Max_Heap_Table_Size cannot be set to 4 gb")
  now throws a warning on 32-bit, as it should. As we're not
  actually interested in the warning but only in whether the
  variable is set to a correct value afterwards, we disable
  warnings for the duration of that test case so we won't have
  to split the test into a 32-bit and a 64-bit flavour for no
  real reason.

Would not prevent mysqld from core dumping
Passes --nocore arg to safe_process, which then sets rlimit core to 0 for child

Retried tests are reported the same as ordinary ones
Prepend "retry-" to fail or pass for retried tests