dded init of variable to fix core dump on startup errors

(found during BUG#1708 investigation)

(test suite will be with next part)

into serg.mylan:/usr/home/serg/Abk/mysql-4.1

into mysql.com:/home/kostja/mysql/mysql-4.1-root

and was removed from THD

into serg.mylan:/usr/home/serg/Abk/mysql-4.1

into gw.mysql.r18.ru:/usr/home/ram/work/4.1.wl1056

into gw.mysql.r18.ru:/usr/home/ram/work/4.1.wl1279

Bug #1707: mysqldump -X does't quote field and table names
code cleanup

Fixed. Enabled test case in client_test.c.

into mysql.com:/home/pem/work/mysql-4.1

code cleanup

into sanja.is.com.ua:/home/bell/mysql/bk/work-qc_warn-4.1

  Fix yet another race condition in sql_parse.cc: thd->user_connect object could get deleted too soon, before the call of check_for_max_user_connections

  Add diagnostic printf to chack that number of connections for a user never drops below zero

And added new test for BUG#1644. (Disabled for now, not fixed yet.)

Note:
- All test results haven't been inspected in detail to see if they are correct.
- Some result set printing seems to have the wrong field width; most notably
  date/time fields and type fields (e.g. "int(4)").
- There are still some valgrind complaints, but they seem to be in assert() or
  in libmysql.

into sanja.is.com.ua:/home/bell/mysql/bk/work-4.1

into sanja.is.com.ua:/home/bell/mysql/bk/work-4.1

  URGENT: MONTY AND SERGEI should check this patch! The patch fixes the memory corruption reported by a user. It happened because the code did not keep correct a count of how many connections a user has, and the user object got freed too soon if the same user had more than 1 connection. Also fix a typo by Sanja: 'and' is not a C operator, I think it should be &&