manual merge. also adds test specific to 5.1+

mysql-test/suite/rpl/r/rpl_temporary.result:
  show that a non-privileged user trying to
  kill system-threads no longer crashes the
  server. test in 5.1+ only.
mysql-test/suite/rpl/t/rpl_temporary.test:
  show that a non-privileged user trying to
  kill system-threads no longer crashes the
  server. test in 5.1+ only.
sql/sql_class.cc:
  manual merge
sql/sql_class.h:
  manual merge
sql/sql_parse.cc:
  manual merge