routine does not exist 
      
There is an inconsistency with DROP DATABASE IF EXISTS, DROP TABLE IF
EXISTS and DROP VIEW IF EXISTS: those are binlogged even if the DB or
TABLE does not exist, whereas DROP PROCEDURE IF EXISTS does not. It
would be nice or at least consistent if DROP PROCEDURE/STATEMENT
worked the same too.
      
Fixed DROP PROCEDURE|FUNCTION IF EXISTS by adding a call to
mysql_bin_log.write in mysql_execute_command. Checked also if all 
documented "DROP (...) IF EXISTS" get binlogged.
      
NOTE: This is a 5.0 backport patch as requested by support.

mysql-test/r/rpl_drop_if_exists.result:
  Result file for test case added.
mysql-test/r/rpl_sp.result:
  Updated result file for existing test case that has now extra events in
  binary log (the ones from drop if exists procedure/function).
mysql-test/t/rpl_drop_if_exists.test:
  Added test case for asserting validity of proposed patch.
sql/sql_parse.cc:
  Added call mysql_bin_log.write when lex has drop_if_exists enabled for 
  stored procedures.