The function CRC32() returns unsigned integer.
But the metadata (the unsigned flag) for the 
function was set incorrectly.
As a result type arithmetics based on the 
function's metadata (like finding the concise
type of an temporary table column to hold the result)
returned incorrect results.
Fixed by returning correct type information.

This fix is based on code contributed by Martin Friebe
(martin@hybyte.com) on 2007-03-30.  


mysql-test/r/func_str.result:
  Bug #27530: test case
mysql-test/t/func_str.test:
  Bug #27530: test case
sql/item_strfunc.h:
  Bug #27530: Marked CRC32() as returning unsigned