branches/zip: Restore the transaction commit that was removed in r1583.

ha_innobase::add_index(): Do commit the transaction, because the error
handler (label err1) in mysql_alter_table() won't commit it as of now.
This was detected in a failure of type_bit_innodb.

handler/ha_innodb.cc

@@ -8361,6 +8361,7 @@ error_handling:
 
 func_exit:
 	mem_heap_free(heap);
+	innobase_commit_low(trx);/* work around a bug in mysql_alter_table() */
 
 	/* There might be work for utility threads.*/
 	srv_active_wake_master_thread();