Adding decimal "digits" in multiplication resulted in signed overflow and
producing wrong results.

  Fixed by using large enough buffers and intermediary result types :
dec2 (currently longlong) to hold result of adding decimal "digits" 
(currently int32). 

into moonbone.local:/work/merge-5.0

into  poseidon.ndb.mysql.com:/home/tomas/5.0-merge

into  poseidon.ndb.mysql.com:/home/tomas/5.0-merge

into moonbone.local:/work/merge-4.1

into  poseidon.ndb.mysql.com:/home/tomas/mysql-4.1-main

into  poseidon.ndb.mysql.com:/home/tomas/mysql-5.0-main

into  poseidon.ndb.mysql.com:/home/tomas/mysql-5.0-main

into  poseidon.ndb.mysql.com:/home/tomas/mysql-5.0

into  poseidon.ndb.mysql.com:/home/tomas/5.0-merge

Re-apply a patch by Knielsen in the 5.0.23 build clone: Replace port number by "SLAVE_PORT".

into  mysql.com:/opt/local/work/mysql-5.0-runtime

into  mysql.com:/users/lthalmann/bkroot/mysql-5.0-release

into  mysql.com:/opt/local/work/mysql-5.0-runtime

into  mysql.com:/opt/local/work/mysql-5.0-runtime

into  mysql.com:/home/stewart/Documents/MySQL/4.1/main

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

into  mysql.com:/users/lthalmann/bkroot/mysql-5.0-release

into  mysql.com:/home/stewart/Documents/MySQL/5.0/main

into  mysql.com:/opt/local/work/mysql-5.0-runtime

into  perch.ndb.mysql.com:/home/jonas/src/mysql-5.0-release

into  poseidon.ndb.mysql.com:/home/tomas/mysql-5.0-main

into  poseidon.ndb.mysql.com:/home/tomas/mysql-5.0-main

+ adopted signal to be as close as possible to 5.1...

  Fix compile error for forte

into  mysql.com:/data0/knielsen/tmp-5.0

into  mysql.com:/home/kgeorge/mysql/5.0/warnings

into  mysql.com:/home/kgeorge/mysql/4.1/warnings

into  mysql.com:/home/tomash/src/mysql_ab/mysql-5.0-bug10946

It was hard to distinguish case, when one was unable to create trigger
on the table because trigger with same action time and event already
existed for this table, from the case, when one tried to create trigger
with name which was already occupied by some other trigger, since in
both these cases we emitted ER_TRG_ALREADY_EXISTS error and message.
Now we emit ER_NOT_SUPPORTED_YET error with appropriate additional
message in the first case. There is no sense in introducing separate
error for this situation since we plan to get rid of this limitation
eventually.

No test case as the bug is in an existing test case (rpl_trigger.test
when it is run under valgrind).
The warning was caused by memory corruption in replication slave: thd->db
was pointing at a stack address that was previously used by 
sp_head::execute()::old_db. This happened because mysql_change_db
behaved differently in replication slave and did not make a copy of the 
argument to assign to thd->db. 
The solution is to always free the old value of thd->db and allocate a new
copy, regardless whether we're running in a replication slave or not.