Problem: when embedding a character string with introducer with charset X
into a SQL query which is generally in character set Y, the string constants
were escaped according to their own character set (i.e.X), then after reading
such a "mixed" query from binlog, the string constants were unescaped
using character set of the query (i.e. Y), instead of X, which gave wrong
results or even syntax errors with tricky charsets (e.g. sjis)
Fix: when embedding a string constant of charset X into a query of charset Y,
the string constant is now escaped according to character Y, instead of
its own character set X.


mysql-test/r/ctype_cp932_binlog.result:
  Fixing test results.
sql/log_event.cc:
  Using character set "csinfo" instead of the string character set.
sql/sp_head.cc:
  - adding "thd" argument to sp_get_item_value()
    to have access to thd->variables.character_set_client
  - using character_set_client for escaping, instead of
    the string character set
mysql-test/r/rpl_charset_sjis.result:
  Adding test case
mysql-test/t/rpl_charset_sjis.test:
  Adding test case