Generating character set-independent quoting of strings for the
binary log when executing statements from inside stored procedure.


mysql-test/r/ctype_cp932_binlog.result:
  Result change
mysql-test/t/ctype_cp932_binlog.test:
  Adding check that string literals are written correctly for multi-byte
  character sets.
sql/item.cc:
  Cutting out character set-independent string escaping code and putting it
  in a separate function.
sql/log_event.cc:
  Adding characters set-independent code to separate function.
sql/mysql_priv.h:
  Adding new function.
sql/sp_head.cc:
  Escaping string value representing a string item.