Review comments


sql/item.h:
  Added comment after review
sql/item_cmpfunc.h:
  Changed to either return TRUE or FALSE (check_partition_func_processor)
sql/item_func.h:
  Changed to either return TRUE or FALSE (check_partition_func_processor)
sql/item_strfunc.h:
  Changed to either return TRUE or FALSE (check_partition_func_processor)
sql/item_timefunc.h:
  Changed to either return TRUE or FALSE (check_partition_func_processor)
sql/item_xmlfunc.h:
  Changed to either return TRUE or FALSE (check_partition_func_processor)