added error_code to query event, and checking to see if we get the
expected error on the slave
removed obsolete code from slave.cc


sql/log_event.cc:
  added mutex as an argument to FILE read_log_event functions
sql/log_event.h:
  added error_code for the query event
sql/mysqlbinlog.cc:
  fix for new form of read_log_event
sql/slave.cc:
  removed obsolte code with fetch nx table
  added check to see if the query runs with the same error on the slave
  as it did on the master
sql/sql_repl.cc:
  fixed mutex problem around read_log_event