After merge fixes
Portability fixes


client/mysqltest.c:
  Fixed that unget() is done properly (needed for QNX where one can't do many ungetc() in a row)
include/errmsg.h:
  After merge fixes
mysql-test/mysql-test-run.sh:
  merge fix
mysql-test/r/system_mysql_db.result:
  Updated results for 4.1
mysql-test/r/union.result:
  Added new test
mysql-test/t/derived.test:
  Portability fix (for Mac OS X)
mysql-test/t/system_mysql_db_refs.test:
  Remove warnings
mysql-test/t/union.test:
  Added test to show bug in current union implementation (to be fixed in 4.1)
scripts/mysql_create_system_tables.sh:
  Fix wrong column define
scripts/mysql_fix_privilege_tables.sh:
  Fix for mysql-test-run
scripts/mysql_fix_privilege_tables.sql:
  Merge with 4.0 to get comments.
  Updated so that it works with privilege tables for MySQL 3.23.
sql/repl_failsafe.cc:
  After merge fix