into  zippy.cornsilk.net:/home/cmiller/work/mysql/bug21476/my51-bug21476

The STACK_MIN_SIZE is currently set to 8192, when we actually need 
(emperically discovered) 9236 bytes to raise an fatal error, on Ubuntu 
Dapper Drake, libc6 2.3.6-0ubuntu2, Linux kernel 2.6.15-27-686, on x86.

I'm taking that as a new lower bound, plus 100B of wiggle-room for sundry
word sizes and stack behaviors.

The added test verifies in a cross-platform way that there are no gaps 
between the space that we think we need and what we actually need to report 
an error.

DOCUMENTERS:  This also adds "let" to the mysqltest commands that evaluate
an argument to expand variables therein.  (Only right of the "=", of course.)

into  zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-5.1-maint

into  mysql.com:/users/lthalmann/bkroot/mysql-5.1

into  mysql.com:/users/lthalmann/bk/MERGE/mysql-5.1-merge

into  mysql.com:/users/lthalmann/bk/MERGE/mysql-5.0-merge

into  mysql.com:/users/lthalmann/bk/MERGE/mysql-5.0-merge

into  mysql.com:/users/lthalmann/bk/MERGE/mysql-4.1-merge

into  mysql.com:/users/lthalmann/bk/MERGE/mysql-5.1-merge

into  mysql.com:/users/lthalmann/bk/MERGE/mysql-5.0-merge

into  mysql.com:/users/lthalmann/bk/MERGE/mysql-4.1-merge

into  mysql.com:/windows/Linux_space/MySQL/mysql-5.1

into  polly.local:/home/kaa/src/maint/m51-new-maint--07OGx

into  polly.local:/tmp/22129/bug22129/my51-bug22129

into  polly.local:/tmp/22129/bug22129/my50-bug22129

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

Better checks for underflow/overflow

into  dsl-hkigw8-feb9fb00-191.dhcp.inet.fi:/home/elkin/MySQL/TEAM/BARE/mysql-5.1-new-rpl

local file slipped into a previous commit, fixing ignore.

 - Variables must be declared first in each block

into  bk-internal.mysql.com:/tmp/knielsen/mysql-5.1-new-maint

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

 - Void function can't return a value

into  shellback.(none):/home/msvensson/mysql/mysql-5.1-maint

into  shellback.(none):/home/msvensson/mysql/mysql-5.1-maint

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

into  romeo.(none):/home/bkroot/mysql-5.1-new-rpl

Using move_field_offset() to move field pointer to other record before
calling pack()/unpack().

into  chilla.local:/home/mydev/mysql-5.0-toteam

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

Fixed udf_example, so tests now can also run udf on win.

into  mysql.com:/users/lthalmann/bk/MERGE/mysql-5.1-merge