Bug #50942 mix_innodb_myisam_side_effects.test is not deterministic

The test was used to fail because of 
 UPDATE t3,t4 SET t3.a=t4.a + bug27417(1);
did not prescribe the order of two row operations implied by the update.

Fixed with forcing the order with adding a where condition w/o
affecting the former bug fixes logics.

mysql-test/extra/binlog_tests/mix_innodb_myisam_side_effects.test

@@ -214,7 +214,7 @@ CREATE TABLE t5 (a int, PRIMARY KEY (a)) ENGINE=InnoDB;
 
 # execute
  --error ER_DUP_ENTRY
- UPDATE t3,t4 SET t3.a=t4.a + bug27417(1);
+ UPDATE t3,t4 SET t3.a = t4.a + bug27417(1) where t3.a = 1;
 
 # check
  select count(*) from t1 /* must be 1 */;

mysql-test/suite/binlog/r/binlog_row_mix_innodb_myisam.result

@@ -879,11 +879,11 @@ delete from t4;
 insert into t3 values (1,1),(2,2);
 insert into t4 values (1,1),(2,2);
 reset master;
-UPDATE t3,t4 SET t3.a=t4.a + bug27417(1);
+UPDATE t3,t4 SET t3.a = t4.a + bug27417(1) where t3.a = 1;
 ERROR 23000: Duplicate entry '2' for key 'PRIMARY'
 select count(*) from t1 /* must be 1 */;
 count(*)
-2
+1
 drop table t4;
 delete from t1;
 delete from t2;

mysql-test/suite/binlog/r/binlog_stm_mix_innodb_myisam.result

@@ -802,7 +802,7 @@ delete from t4;
 insert into t3 values (1,1),(2,2);
 insert into t4 values (1,1),(2,2);
 reset master;
-UPDATE t3,t4 SET t3.a=t4.a + bug27417(1);
+UPDATE t3,t4 SET t3.a = t4.a + bug27417(1) where t3.a = 1;
 ERROR 23000: Duplicate entry '2' for key 'PRIMARY'
 select count(*) from t1 /* must be 1 */;
 count(*)