fixes for SLES10


mysql-test/r/change_user.result:
  It's unsigned.
mysys/my_getopt.c:
  Failsafe no longer needed, we handle signedness correctly now.
sql/set_var.cc:
  ha_rows can be derived from all kinds of types, but
  they're all unsigned. Display it as such.
tests/mysql_client_test.c:
  cannot easily check this here due to types.
  check with Alik whether we need this on top
  of change_user.test.