/*![:version:] Query Code */, where [:version:] is a sequence of 5 
digits representing the mysql server version(e.g /*!50200 ... */),
is a special comment that the query in it can be executed on those 
servers whose versions are larger than the version appearing in the 
comment. It leads to a security issue when slave's version is larger 
than master's. A malicious user can improve his privileges on slaves. 
Because slave SQL thread is running with SUPER privileges, so it can
execute queries that he/she does not have privileges on master.

This bug is fixed with the logic below: 
- To replace '!' with ' ' in the magic comments which are not applied on
  master. So they become common comments and will not be applied on slave.

- Example:
  'INSERT INTO t1 VALUES (1) /*!10000, (2)*/ /*!99999 ,(3)*/
  will be binlogged as
  'INSERT INTO t1 VALUES (1) /*!10000, (2)*/ /* 99999 ,(3)*/

mysql-test/suite/rpl/t/rpl_conditional_comments.test:
  Test the patch for this bug.
sql/mysql_priv.h:
  Rename inBuf as rawBuf and remove the const limitation.
sql/sql_lex.cc:
  To replace '!' with ' ' in the magic comments which are not applied on
  master.
sql/sql_lex.h:
  Remove the const limitation on parameter buff, as it can be modified in the function since
  this patch.
  Add member function yyUnput for Lex_input_stream. It set a character back the query buff.
sql/sql_parse.cc:
  Rename inBuf as rawBuf and remove the const limitation.
sql/sql_partition.cc:
  Remove the const limitation on parameter part_buff, as it can be modified in the function since
  this patch.
sql/sql_partition.h:
  Remove the const limitation on parameter part_buff, as it can be modified in the function since
  this patch.
sql/table.h:
  Remove the const limitation on variable partition_info, as it can be modified since
  this patch.