item.cc:
item.h:
  Adding Item_param::safe_charset_converter,
  not to return collation mix error if
  parameter can be converted into operation
  character set.

ctype_utf8.result:
  adding test case
ctype_utf8.test:
  adding test case


sql/item.h:
  Bug #12371 executing prepared statement fails (illegal mix of collations)
  Adding Item_param::safe_charset_converter,
  not to returm collation mix error if
  parameter can be converted into operation
  character set.
sql/item.cc:
  Bug #12371 executing prepared statement fails (illegal mix of collations)
mysql-test/t/ctype_utf8.test:
  adding test case
mysql-test/r/ctype_utf8.result:
  adding