old upgrade behaviour.
Add test for upgrade from 5.0.30


mysql-test/t/system_mysql_db_fix40123.test:
  Drop alos the new 5.1 tables after test
scripts/mysql_fix_privilege_tables.sql:
  Update 5.1 version of mysql_fix_privilege_tables.sql to also do 
  an "ALTER TABLE MODIFY" on the new column(s) it adds. This allows us to 
  make sure that both new and already existing columsn get the right type.
mysql-test/t/system_mysql_db_fix50030-master.opt:
  New BitKeeper file ``mysql-test/t/system_mysql_db_fix50030-master.opt''
mysql-test/t/system_mysql_db_fix50030.test:
  New BitKeeper file ``mysql-test/t/system_mysql_db_fix50030.test''