In cp932, '\' character can be the second byte in a 
multi-byte character stream. This makes it difficult to use
mysql_escape_string. Added flag to indicate which languages allow
'\' as second byte of multibyte sequence so that when putting a prepared
statement into the binlog we can decide at runtime whether hex encoding
is really needed.


include/m_ctype.h:
  Added bool to indicate character sets which allow '\' as the second
  byte of a multibyte character set (currently only cp932). For these
  character sets, escaping with '\' is dangerous and leads to corruption
  in replication.
include/my_sys.h:
  Add function to enocde a string as hex with no prefix (bare)
mysys/charset.c:
  Add function to encode string as hex with no prefix (bare).
sql/item.cc:
  Check the connection character set to see if escape_string_for_mysql
  is safe, or if character set requires unambiguous (hex) encoding
sql/item.h:
  Pass thd to query_val_str for access to charset()
sql/sql_prepare.cc:
  Pass thd to query_val_str.
strings/ctype-big5.c:
  Add escape_with_backslash_is_dangerous flag.
strings/ctype-bin.c:
  Add escape_with_backslash_is_dangerous flag
strings/ctype-cp932.c:
  Add escape_with_backslash_is_dangerous flag.
strings/ctype-czech.c:
  Add escape_with_backslash_is_dangerous flag.
strings/ctype-euc_kr.c:
  Add escape_with_backslash_is_dangerous flag.
strings/ctype-extra.c:
  Add escape_with_backslash_is_dangerous flag.
strings/ctype-gb2312.c:
  Add escape_with_backslash_is_dangerous flag.
strings/ctype-gbk.c:
  Added escape_with_backslash_is_dangerous flag.
strings/ctype-latin1.c:
  Added escape_with_backslash_is_dangerous flag.
strings/ctype-sjis.c:
  Added escape_with_backslash_is_dangerous flag.
strings/ctype-tis620.c:
  Added esacpe_with_backslash_character_is_dangerous flag.
strings/ctype-uca.c:
  Added escape_with_backslash_is_dangerous flag.
strings/ctype-ucs2.c:
  Added escape_with_backslash_is_dangerous.
strings/ctype-ujis.c:
  Added escape_with_backslash_is_dangerous flag.
strings/ctype-utf8.c:
  Added escape_with_backslash_is_dangerous.
strings/ctype-win1250ch.c:
  Added escape_with_backslash_is_dangerous.