mysql-test/r/ps.result:
  Test results fixed: the test case for bug#5688 "Upgraded 4.1.5 Server 
  seg faults"
mysql-test/t/ps.test:
  Test case for bug#5688 "Upgraded 4.1.5 Server seg faults"
sql/item_cmpfunc.cc:
  A fix for bug#5688 "Upgraded 4.1.5 Server seg faults":
  fix just another place where we use wrong memory root for an Item
  in statement prepare.
  In addition, make the check for charsets in Item_bool_func2
  more generic (fixes the test case when we use LIKE to compare BLOBs
  with TEXT data).