Reorder structure elements to make structures smaller and faster on 64 bit systems
This is a first step in cleaning up the client include files (but should be enough to allow us to do future fixes without breaking the library)
This change is part of WL#2872,  Make client library extensible.

Now we don't take any mutexes when creating or dropping internal HEAP tables during SELECT.
Change buffer sizes to size_t to make keycache 64 bit safe on platforms where sizeof(ulong) != sizeof(size_t)

into  mysql.com:/home/my/mysql-5.1

into  trift2.:/MySQL/M51/push-5.1

into  mysql.com:/home/kent/bk/tmp3/mysql-5.0-build

into  mysql.com:/home/kent/bk/tmp3/mysql-5.1-build

into  gleb.loc:/home/uchum/work/bk/5.1-opt

into  moonbone.local:/mnt/gentoo64/work/29898-bug-5.0-opt-mysql

into  trift-lap.none:/MySQL/M51/push-5.1

into  trift-lap.none:/MySQL/M50/push-5.0

into  trift-lap.none:/MySQL/M51/push-5.1

into  pippilotta.erinye.com:/shared/home/df/mysql/build/mysql-5.1-build

into  pippilotta.erinye.com:/shared/home/df/mysql/build/mysql-5.0-build

into  gleb.loc:/home/uchum/work/bk/5.1-opt

into  gleb.loc:/home/uchum/work/bk/5.1-opt

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

into  gleb.loc:/home/uchum/work/bk/5.1-opt

into  pippilotta.erinye.com:/shared/home/df/mysql/build/mysql-5.0.46

The Item_date_typecast::val_int function doesn't reset null_value flag.
This makes all values that follows the first null value to be treated as nulls
and led to a wrong result.

Now the Item_date_typecast::val_int function correctly sets the null_value flag
for both null and non-null values.

into  trift2.:/MySQL/M51/push-5.1

into  trift2.:/MySQL/M51/push-5.1

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

into  moonbone.local:/mnt/gentoo64/work/29850-bug-5.0-opt-mysql

a temporary table.

The result string of the Item_func_group_concat wasn't initialized in the 
copying constructor of the Item_func_group_concat class. This led to a
wrong charset of GROUP_CONCAT result when the select employs a temporary
table.

The copying constructor of the Item_func_group_concat class now correctly
initializes the charset of the result string.

into  mysql.com:/home/hf/work/29687/my51-29687

into  mysql.com:/home/hf/work/29687/my51-29687

into  mysql.com:/home/hf/work/29687/my50-29687

into  mysql.com:/home/hf/work/29687/my50-29687

into  mysql.com:/home/hf/work/29687/my51-29687

into  bk-internal.mysql.com:/data0/bk/tsmith-tmp/mysql-5.1-maint

into  bk-internal.mysql.com:/data0/bk/tsmith-tmp/mysql-5.0-maint

into  gleb.loc:/home/uchum/work/bk/5.1-opt

into  gleb.loc:/home/uchum/work/bk/5.1-opt

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

into  trift-lap.none:/MySQL/M51/bug14151-5.1

by renaming "include/md5.h" to "include/my_md5.h".

Fixes bug#14151.