- Add a check to see if the .mysql_history file a symlink to /dev/null 
   and in such case, skip reading and writing to it. 
     


client/mysql.cc:
  Add check to detect if the "mysql_history" file is a symlink to /dev/null.
  In that case, don't create histfile variable.
  That will make read_history and write_history to be skipped.