buffer for a MY_BITMAP temporary buffer allocated on stack in the
function get_best_covering_ror_intersect().
Now the buffer of a proper size is allocated by a request from this
function in mem_root.

We succeeded to demonstrate the bug only on Windows with a very large
database. That's why no test case is provided for in the patch.


sql/opt_range.cc:
  Fixed bug 16201: a memory corruption causing crashes due to a too small 
  buffer for a MY_BITMAP temporary buffer allocated on stack in the
  function get_best_covering_ror_intersect().
  Now the buffer of a proper size is allocated by a request from this
  function in mem_root.