branches/zip: ha_innobase::add_index(): Do not commit the transaction.

It should be committed by MySQL after all.  The error in mysql_alter_table()
will be worked around in r1584.

handler/ha_innodb.cc

@@ -8373,7 +8373,6 @@ ha_innobase::add_index(
 
 func_exit:
 	mem_heap_free_noninline(heap);
-	innobase_commit_low(trx);
 
 	/* There might be work for utility threads.*/
 	srv_active_wake_master_thread();