another cleanup patch for removing tables before tests start.

mysql-test/extra/binlog_tests/insert_select-binlog.test:
  Fixing isssues with preexisting tables
mysql-test/r/binlog_stm_insert_select.result:
  new results

mysql-test/extra/binlog_tests/insert_select-binlog.test

 # Embedded server doesn't support binlog
 -- source include/not_embedded.inc
 
+--disable_warnings
+drop table if exists t1,t2;
+--enable_warnings
+
 # Check if a partly-completed INSERT SELECT in a MyISAM table goes into the
 # binlog
 

mysql-test/r/binlog_stm_insert_select.result

+drop table if exists t1,t2;
 create table t1(a int, unique(a));
 insert into t1 values(2);
 create table t2(a int);