server': the bug occurs when arguments of LIKE function are in 
differentcharacter sets. If these character sets are compatible, 
we create an item-converter. In prepared mode, this item
needs to be created in memory of current prepared statement.


mysql-test/r/ps.result:
  Test for Bug#4368 added.
mysql-test/t/ps.test:
  A test case for bug#4368 '"like" fails in PreparedStatement, 
  crashes server'.